diff --git a/src/main/java/com/gtnewhorizons/postea/Postea.java b/src/main/java/com/gtnewhorizons/postea/Postea.java
index 50d3877..cf55f7a 100644
--- a/src/main/java/com/gtnewhorizons/postea/Postea.java
+++ b/src/main/java/com/gtnewhorizons/postea/Postea.java
@@ -1,6 +1,7 @@
 package com.gtnewhorizons.postea;
 
 import com.gtnewhorizons.postea.utility.MissingMappingHandler;
+import com.gtnewhorizons.postea.utility.SimpleTransformationRegistry;
 import com.gtnewhorizons.postea.utility.TransformerRegistry;
 
 import cpw.mods.fml.common.Mod;
@@ -27,7 +28,8 @@ public class Postea {
 
     @Mod.EventHandler
     public void onIdMappingsChanged(FMLModIdMappingEvent event) {
-        TransformerRegistry.onIdMappingsChanged(event);
+        SimpleTransformationRegistry.onIdMappingsChanged();
+        TransformerRegistry.onIdMappingsChanged();
     }
 
     @Mod.EventHandler
@@ -37,7 +39,7 @@ public class Postea {
 
     @Mod.EventHandler
     public void onLoadCompleted(FMLLoadCompleteEvent event) {
-        TransformerRegistry.onLoadCompleted();
+        SimpleTransformationRegistry.onLoadCompleted();
         MissingMappingHandler.onLoadCompleted();
     }
 
diff --git a/src/main/java/com/gtnewhorizons/postea/api/BlockReplacementManager.java b/src/main/java/com/gtnewhorizons/postea/api/BlockReplacementManager.java
index 18ed85e..72e66d4 100644
--- a/src/main/java/com/gtnewhorizons/postea/api/BlockReplacementManager.java
+++ b/src/main/java/com/gtnewhorizons/postea/api/BlockReplacementManager.java
@@ -11,6 +11,7 @@ import net.minecraftforge.oredict.OreDictionary;
 
 import com.gtnewhorizons.postea.utility.BlockConversionInfo;
 import com.gtnewhorizons.postea.utility.MissingMappingHandler;
+import com.gtnewhorizons.postea.utility.SimpleTransformationRegistry;
 import com.gtnewhorizons.postea.utility.TransformerRegistry;
 
 public class BlockReplacementManager {
@@ -43,8 +44,9 @@ public class BlockReplacementManager {
      */
     @Deprecated
     @SuppressWarnings("unused")
-    public static void addBlockReplacement(@Nonnull String originalId,
-        @Nonnull BiFunction<BlockConversionInfo, World, BlockConversionInfo> transformer) {
+    public static void addBlockReplacement(String originalId,
+        BiFunction<BlockConversionInfo, World, BlockConversionInfo> transformer) {
+        if (transformer == null) throw new IllegalArgumentException("transformer is null");
         addTransformationHandler(originalId, info -> transformer.apply(info, info.world) != null);
     }
 
@@ -73,8 +75,7 @@ public class BlockReplacementManager {
      * @param transformer The transformer to apply.
      */
     @SuppressWarnings("unused")
-    public static void addTransformationHandler(@Nonnull String originalId,
-        @Nonnull Function<BlockConversionInfo, Boolean> transformer) {
+    public static void addTransformationHandler(String originalId, Function<BlockConversionInfo, Boolean> transformer) {
         if (originalId == null) throw new IllegalArgumentException("original id is null");
         if (transformer == null) throw new IllegalArgumentException("transformer is null");
         TransformerRegistry.addBlockReplacement(originalId, transformer);
@@ -93,7 +94,7 @@ public class BlockReplacementManager {
      * @param block      The block to remap to.
      */
     @SuppressWarnings("unused")
-    public static void replaceMissingBlockWithNewBlock(@Nonnull String originalId, @Nonnull Block block) {
+    public static void replaceMissingBlockWithNewBlock(String originalId, Block block) {
         if (originalId == null) throw new IllegalArgumentException("original id is null");
         if (block == null) throw new IllegalArgumentException("block is null");
         MissingMappingHandler.addSimpleReplacement(originalId, block);
@@ -239,10 +240,10 @@ public class BlockReplacementManager {
      * @param skipStackRemap Set to true to skip auto-adding an item stack remapper.
      */
     @SuppressWarnings("unused")
-    public static void addBlockReplacement(@Nonnull String originalId, int originalMeta, @Nonnull Block block,
-        int newMeta, boolean skipStackRemap) {
+    public static void addBlockReplacement(String originalId, int originalMeta, Block block, int newMeta,
+        boolean skipStackRemap) {
         if (originalId == null) throw new IllegalArgumentException("original id is null");
         if (block == null) throw new IllegalArgumentException("block is null");
-        TransformerRegistry.addSimpleTransformer(originalId, originalMeta, block, newMeta, skipStackRemap);
+        SimpleTransformationRegistry.addSimpleTransformer(originalId, originalMeta, block, newMeta, skipStackRemap);
     }
 }
diff --git a/src/main/java/com/gtnewhorizons/postea/api/ItemStackReplacementManager.java b/src/main/java/com/gtnewhorizons/postea/api/ItemStackReplacementManager.java
index ec1558a..9c5f4d5 100644
--- a/src/main/java/com/gtnewhorizons/postea/api/ItemStackReplacementManager.java
+++ b/src/main/java/com/gtnewhorizons/postea/api/ItemStackReplacementManager.java
@@ -1,9 +1,9 @@
 package com.gtnewhorizons.postea.api;
 
+import java.util.function.BiFunction;
 import java.util.function.Function;
 
 import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
 
 import net.minecraft.init.Items;
 import net.minecraft.item.Item;
@@ -12,109 +12,17 @@ import net.minecraft.nbt.NBTTagCompound;
 import net.minecraftforge.oredict.OreDictionary;
 
 import com.gtnewhorizons.postea.utility.MissingMappingHandler;
+import com.gtnewhorizons.postea.utility.SimpleTransformationRegistry;
 import com.gtnewhorizons.postea.utility.TransformerRegistry;
 
 public class ItemStackReplacementManager {
 
     // Public API for converting ItemStacks.
 
-    // spotless:off
-    /**
-     * Fetches the original registration name of a given item id. Use this to get the actual name of an item when migrating
-     * an item that no longer exists.
-     *
-     * @apiNote This only works for items that have been registered for Postea transformations, and should not be used
-     *          outside a Postea transformer function.
-     *          <pre>{@code
-     *          public static class Example {
-     *              public static void postLoad() {
-     *                  ItemStackReplacementManager.addTransformationHandler("removedmod:item1", Example::transform);
-     *                  ItemStackReplacementManager.addTransformationHandler("removedmod:item2", Example::transform);
-     *                  ItemStackReplacementManager.addTransformationHandler("removedmod:item3", Example::transform);
-     *              }
-     *
-     *              public static boolean transform(NBTTagCompound tag) {
-     *                  // consider using the other addItemReplacement functions without a function
-     *                  // They create very fast transformers that run in constant time
-     *                  // regardless of how many transformations you register to a single id
-     *                  short meta = tag.getShort("Damage");
-     *                  switch (ItemStackReplacementManager.getOriginalItemName(tag)) {
-     *                      int meta = 0;
-     *                      case "removedmod:item1":
-     *                          if (meta != 0) return false;
-     *                          meta = 1;
-     *                          break;
-     *                      case "removedmod:item2":
-     *                          meta = 2;
-     *                          break;
-     *                  }
-     *                  IDExtenderCompat.setItemStackID(tag, Items.getIdFromItem(MyItems.item1));
-     *                  tag.setShort("Damage", meta);
-     *                  return true;
-     *              }
-     *          }
-     *          }<pre/>
-     *
-     * @param tag The NBT tag that was passed to your handler.
-     * @return The original namespaced name of the item being transformed.
-     */
-    // spotless:on
-    @SuppressWarnings("unused")
-    public static @Nullable String getOriginalItemName(NBTTagCompound tag) {
-        return TransformerRegistry.getMappedItemName(IDExtenderCompat.getItemStackID(tag));
-    }
-
-    // spotless:off
-    /**
-     * Fetches the original registration name of a given item id. Use this to get the actual name of an item when
-     * migrating an item that no longer exists.
-     *
-     * @apiNote This only works for items that have been registered for Postea transformations, and should not be used
-     *          outside a Postea transformer function.
-     *          <pre>{@code
-     *          public static class Example {
-     *              public static void postLoad() {
-     *                  ItemStackReplacementManager.addTransformationHandler("removedmod:item1", Example::transform);
-     *                  ItemStackReplacementManager.addTransformationHandler("removedmod:item2", Example::transform);
-     *                  ItemStackReplacementManager.addTransformationHandler("removedmod:item3", Example::transform);
-     *              }
-     *
-     *              public static boolean transform(NBTTagCompound tag) {
-     *                  // consider using the other addItemReplacement functions without a function
-     *                  // They create very fast transformers that run in constant time
-     *                  // regardless of how many transformations you register to a single id
-     *                  short meta = tag.getShort("Damage");
-     *                  int id = IDExtenderCompat.getItemStackID(tag);
-     *                  switch (ItemStackReplacementManager.getOriginalItemName(id)) {
-     *                      int meta = 0;
-     *                      case "removedmod:item1":
-     *                          if (meta != 0) return false;
-     *                          meta = 1;
-     *                          break;
-     *                      case "removedmod:item2":
-     *                          meta = 2;
-     *                          break;
-     *                  }
-     *                  IDExtenderCompat.setItemStackID(tag, Items.getIdFromItem(MyItems.item1));
-     *                  tag.setShort("Damage", meta);
-     *                  return true;
-     *              }
-     *          }
-     *          }<pre/>
-     *
-     * @param itemId The numeric id of the item that was passed to your transformation handler.
-     * @return The original namespaced name of the item being transformed.
-     */
-    // spotless:on
-    @SuppressWarnings("unused")
-    public static @Nullable String getOriginalItemName(int itemId) {
-        return TransformerRegistry.getMappedItemName(itemId);
-    }
-
     /**
      * Adds a custom transformer for a given id.
      *
-     * @deprecated Use {@link #addTransformationHandler(String, Function)} instead.
+     * @deprecated Use {@link #addTransformationHandler(String, BiFunction)} instead.
      *
      * @apiNote When the transformer function passed to this function returns a null, value Postea will assume that
      *          the transformer has failed to identify and run the handler on any other handler function registered
@@ -139,9 +47,9 @@ public class ItemStackReplacementManager {
      */
     @Deprecated
     @SuppressWarnings("unused")
-    public static void addItemReplacement(@Nonnull String originalId,
-        @Nonnull Function<NBTTagCompound, NBTTagCompound> transformer) {
-        addTransformationHandler(originalId, tag -> transformer.apply(tag) != null);
+    public static void addItemReplacement(String originalId, Function<NBTTagCompound, NBTTagCompound> transformer) {
+        if (transformer == null) throw new IllegalArgumentException("transformer is null");
+        addTransformationHandler(originalId, (_originalId, tag) -> transformer.apply(tag) != null);
     }
 
     /**
@@ -168,8 +76,8 @@ public class ItemStackReplacementManager {
      * @param transformer The transformer to apply.
      */
     @SuppressWarnings("unused")
-    public static void addTransformationHandler(@Nonnull String originalId,
-        @Nonnull Function<NBTTagCompound, Boolean> transformer) {
+    public static void addTransformationHandler(String originalId,
+        BiFunction<String, NBTTagCompound, Boolean> transformer) {
         if (originalId == null) throw new IllegalArgumentException("original id is null");
         if (transformer == null) throw new IllegalArgumentException("transformer is null");
         TransformerRegistry.addItemReplacement(originalId, transformer);
@@ -187,7 +95,7 @@ public class ItemStackReplacementManager {
      * @param item       The item to remap to.
      */
     @SuppressWarnings("unused")
-    public static void replaceMissingItemWithNewItem(@Nonnull String originalId, @Nonnull Item item) {
+    public static void replaceMissingItemWithNewItem(String originalId, Item item) {
         if (originalId == null) throw new IllegalArgumentException("original id is null");
         if (item == null) throw new IllegalArgumentException("item is null");
         MissingMappingHandler.addSimpleReplacement(originalId, item);
@@ -289,6 +197,8 @@ public class ItemStackReplacementManager {
     /**
      * Adds a mapping to remap stacks of a given item to another item with a given damage/meta value. This also adds a
      * matching block replacement if this item happens to be an ItemBlock.
+     * <br>
+     * DOES NOT COPY NBT FROM STACK.
      *
      * @implNote All transformations registered using this handler are executed in constant time regardless of how many
      *           transformations are registered to a single id.
@@ -308,6 +218,8 @@ public class ItemStackReplacementManager {
 
     /**
      * Adds a mapping to remap stacks of a given item to another item with a given damage/meta value.
+     * <br>
+     * DOES NOT COPY NBT FROM STACK.
      *
      * @implNote All transformations registered using this handler are executed in constant time regardless of how many
      *           transformations are registered to a single id.
@@ -368,6 +280,8 @@ public class ItemStackReplacementManager {
     /**
      * Adds a mapping to remap all stacks of a given item and damage/meta value to another item with a
      * given damage/meta value. This also adds a matching block replacement if this item happens to be an ItemBlock.
+     * <br>
+     * DOES NOT COPY NBT FROM STACK.
      *
      * @implNote All transformations registered using this handler are executed in constant time regardless of how many
      *           transformations are registered to a single id.
@@ -384,6 +298,8 @@ public class ItemStackReplacementManager {
     /**
      * Adds a mapping to remap all stacks of a given item and damage/meta value to another item with a
      * given damage/meta value.
+     * <br>
+     * DOES NOT COPY NBT FROM STACK.
      *
      * @implNote All transformations registered using this handler are executed in constant time regardless of how many
      *           transformations are registered to a single id.
@@ -434,10 +350,10 @@ public class ItemStackReplacementManager {
      * @param skipBlockRemap Set to true to skip auto-adding a item remapper if the .
      */
     @SuppressWarnings("unused")
-    public static void addItemReplacement(@Nonnull String originalId, int originalMeta, @Nonnull Item item, int newMeta,
+    public static void addItemReplacement(String originalId, int originalMeta, Item item, int newMeta,
         boolean skipBlockRemap) {
         if (originalId == null) throw new IllegalArgumentException("original id is null");
         if (item == null) throw new IllegalArgumentException("item is null");
-        TransformerRegistry.addSimpleTransformer(originalId, originalMeta, item, newMeta, skipBlockRemap);
+        SimpleTransformationRegistry.addSimpleTransformer(originalId, originalMeta, item, newMeta, skipBlockRemap);
     }
 }
diff --git a/src/main/java/com/gtnewhorizons/postea/utility/SimpleTransformationRegistry.java b/src/main/java/com/gtnewhorizons/postea/utility/SimpleTransformationRegistry.java
new file mode 100644
index 0000000..a1e219f
--- /dev/null
+++ b/src/main/java/com/gtnewhorizons/postea/utility/SimpleTransformationRegistry.java
@@ -0,0 +1,186 @@
+package com.gtnewhorizons.postea.utility;
+
+import java.util.Map;
+
+import net.minecraft.block.Block;
+import net.minecraft.item.Item;
+import net.minecraft.item.ItemBlock;
+import net.minecraft.nbt.NBTTagCompound;
+import net.minecraftforge.oredict.OreDictionary;
+
+import org.apache.commons.lang3.tuple.Pair;
+
+import com.gtnewhorizons.postea.api.IDExtenderCompat;
+
+import it.unimi.dsi.fastutil.objects.Object2IntOpenHashMap;
+
+/**
+ * A registry for simple item and block transformations. A common use case is mod removal, replacements or deprecations.
+ * When replacing one mod with another in GTNH, we have to migrate most if not all the mod's items and this often means
+ * having to migrate almost every block and item from the original mod.
+ * <hr>
+ * If a mod uses metas to differentiate items (eg: GT5u) that will end up being migrated to separate items, this would
+ * usually result in potentially multiple handlers per item if they are destined to be split into separate mods,
+ * which increases the execution time linearly. The simple transformations uses a better algorithm for these
+ * which is executed in constant time regardless of how many transformations have been assigned to a given id. (mostly
+ * at the cost of higher memory usage due to caching)
+ */
+public class SimpleTransformationRegistry {
+
+    /**
+     * Stores simple block transformations (eg: if old id is # with meta # then turn into item with id # with meta #.)
+     */
+    public static final SimpleTransformationMap<Pair<Block, Short>> SIMPLE_BLOCK_TRANSFORMATION_MAP = new SimpleTransformationMap<>();
+    public static final Object2IntOpenHashMap<Block> RUNTIME_BLOCK_ID_LOOKUP = new Object2IntOpenHashMap<>();
+    /**
+     * Stores simple item transformations (eg: if old id is # with meta # then turn into item with id # with meta #.)
+     */
+    public static final SimpleTransformationMap<Pair<Item, Short>> SIMPLE_ITEM_TRANSFORMATION_MAP = new SimpleTransformationMap<>();
+    public static final Object2IntOpenHashMap<Item> RUNTIME_ITEM_ID_LOOKUP = new Object2IntOpenHashMap<>();
+
+    // region FML Life Cycle handlers
+    /**
+     * Registers 1 handler per targeted ID to minimize the number of handlers. The meta-map is captured to reduce
+     * the execution time of the handlers.
+     */
+    public static void onLoadCompleted() {
+        // add handlers for simple block remaps
+        for (Map.Entry<String, Map<Integer, Pair<Block, Short>>> kv : SIMPLE_BLOCK_TRANSFORMATION_MAP.entrySet()) {
+            Map<Integer, Pair<Block, Short>> subMap = kv.getValue();
+            TransformerRegistry.addBlockReplacement(kv.getKey(), info -> simpleBlockTransformer(info, subMap));
+        }
+        // add handlers for simple item remaps
+        for (Map.Entry<String, Map<Integer, Pair<Item, Short>>> kv : SIMPLE_ITEM_TRANSFORMATION_MAP.entrySet()) {
+            Map<Integer, Pair<Item, Short>> subMap = kv.getValue();
+            TransformerRegistry
+                .addItemReplacement(kv.getKey(), (originalId, tag) -> simpleItemStackTransformer(tag, subMap));
+        }
+    }
+
+    /**
+     * Pre-caches updated block and item IDs for any simple transformation to speed-up the handlers.
+     */
+    public static void onIdMappingsChanged() {
+        RUNTIME_ITEM_ID_LOOKUP.clear();
+        RUNTIME_BLOCK_ID_LOOKUP.clear();
+        for (Map.Entry<String, Map<Integer, Pair<Block, Short>>> kv : SIMPLE_BLOCK_TRANSFORMATION_MAP.entrySet()) {
+            for (Pair<Block, Short> mapping : kv.getValue()
+                .values()) {
+                RUNTIME_BLOCK_ID_LOOKUP.computeIfAbsent(mapping.getKey(), Block::getIdFromBlock);
+            }
+        }
+        for (Map.Entry<String, Map<Integer, Pair<Item, Short>>> kv : SIMPLE_ITEM_TRANSFORMATION_MAP.entrySet()) {
+            for (Pair<Item, Short> mapping : kv.getValue()
+                .values()) {
+                RUNTIME_ITEM_ID_LOOKUP.computeIfAbsent(mapping.getKey(), Item::getIdFromItem);
+            }
+        }
+    }
+    // endregion FML Life Cycle handlers
+
+    // region block transformations
+    /**
+     * Registers a simple Block transformation for a simple 1:1 transformation:
+     * <ul>
+     * <li>block -> block (with same meta)</li>
+     * <li>block -> block with specific meta</li>
+     * <li>block with meta -> block (with same meta)</li>
+     * <li>block with meta -> block with specific meta</li>
+     * </ul>
+     *
+     * @implNote With these simple transformers, it doesn't matter how many transformations are registered to a single
+     *           id, only a single handler will be registered per id during the FMLLoadCompleted event. Replacements
+     *           are by using hash-table lookups so the execution of the transformation should be constant-time
+     *           regardless
+     *           of how many handlers were registered to a single id.
+     *
+     * @param originalId     The original namespaced id of the block to replace.
+     * @param originalMeta   The meta value of the block to replace. OreDictionary.WILDCARD_VALUE acts as a wildcard
+     *                       and fallback if there isn't simple transformation registered for a given meta.
+     * @param newBlock       What block to replace with.
+     * @param newMeta        The meta value of the transformed block. OreDictionary.WILDCARD_VALUE preserves the
+     *                       existing value.
+     * @param skipStackRemap Set to true to skip registering an identical simple item transformation.
+     */
+    public static void addSimpleTransformer(String originalId, int originalMeta, Block newBlock, int newMeta,
+        boolean skipStackRemap) {
+        if (newMeta == -1) newMeta = OreDictionary.WILDCARD_VALUE;
+        SIMPLE_BLOCK_TRANSFORMATION_MAP.put(originalId, originalMeta, Pair.of(newBlock, (short) newMeta));
+        if (!skipStackRemap) {
+            Item item = Item.getItemFromBlock(newBlock);
+            if (item != null) {
+                SIMPLE_ITEM_TRANSFORMATION_MAP.put(originalId, originalMeta, Pair.of(item, (short) newMeta));
+            }
+        }
+    }
+
+    /**
+     * The handler for the simple block transformation.
+     *
+     * @implNote This implementation has constant-time runtime.
+     */
+    private static boolean simpleBlockTransformer(BlockConversionInfo info, Map<Integer, Pair<Block, Short>> metaMap) {
+        Pair<Block, Short> mapping = SimpleTransformationMap.getFromSubmap(metaMap, info.metadata);
+        if (mapping == null) return false;
+        info.blockID = RUNTIME_BLOCK_ID_LOOKUP.computeIfAbsent(mapping.getKey(), Block::getIdFromBlock);
+        if (mapping.getValue() != OreDictionary.WILDCARD_VALUE) {
+            info.metadata = mapping.getValue();
+        }
+        return true;
+    }
+    // endregion block transformations
+
+    // region item transformations
+    /**
+     * Registers a simple Block transformation for a simple 1:1 transformation:
+     * <ul>
+     * <li>item -> item (with same meta)</li>
+     * <li>item -> item with specific meta</li>
+     * <li>item with meta/damage -> item (with same meta/damage)</li>
+     * <li>item with meta/damage -> item with specific meta/damage</li>
+     * </ul>
+     *
+     * @implNote With these simple transformers, it doesn't matter how many transformations are registered to a single
+     *           id, only a single handler will be registered per id during the FMLLoadCompleted event. Replacements
+     *           are by using hash-table lookups so the execution of the transformation should be constant-time
+     *           regardless
+     *           of how many handlers were registered to a single id.
+     *
+     * @param originalId     The original namespaced id of the item to replace.
+     * @param originalMeta   The meta/damage value of the item to replace. OreDictionary.WILDCARD_VALUE acts as a
+     *                       wildcard
+     *                       and fallback if there isn't simple transformation registered for a given meta.
+     * @param newItem        What item to replace with.
+     * @param newMeta        The meta/damage value of the transformed item. OreDictionary.WILDCARD_VALUE preserves the
+     *                       existing
+     *                       value.
+     * @param skipBlockRemap Set to true to skip registering an identical block transformation if the item is an
+     *                       ItemBlock.
+     */
+    public static void addSimpleTransformer(String originalId, int originalMeta, Item newItem, int newMeta,
+        boolean skipBlockRemap) {
+        if (newMeta == -1) newMeta = OreDictionary.WILDCARD_VALUE;
+        if (!skipBlockRemap && newItem instanceof ItemBlock ib) {
+            SIMPLE_BLOCK_TRANSFORMATION_MAP.put(originalId, originalMeta, Pair.of(ib.field_150939_a, (short) newMeta));
+        }
+        SIMPLE_ITEM_TRANSFORMATION_MAP.put(originalId, originalMeta, Pair.of(newItem, (short) newMeta));
+    }
+
+    /**
+     * The handler for the simple item transformation.
+     *
+     * @implNote This implementation has constant-time runtime.
+     */
+    private static boolean simpleItemStackTransformer(NBTTagCompound tag, Map<Integer, Pair<Item, Short>> metaMap) {
+        short meta = tag.getShort("Damage");
+        Pair<Item, Short> mapping = SimpleTransformationMap.getFromSubmap(metaMap, meta);
+        if (mapping == null) return false;
+        IDExtenderCompat
+            .setItemStackID(tag, RUNTIME_ITEM_ID_LOOKUP.computeIfAbsent(mapping.getKey(), Item::getIdFromItem));
+        if (mapping.getValue() != OreDictionary.WILDCARD_VALUE) {
+            tag.setShort("Damage", mapping.getValue());
+        }
+        return true;
+    }
+    // endregion item transformations
+}
diff --git a/src/main/java/com/gtnewhorizons/postea/utility/TransformerRegistry.java b/src/main/java/com/gtnewhorizons/postea/utility/TransformerRegistry.java
index dcb5348..85e1027 100644
--- a/src/main/java/com/gtnewhorizons/postea/utility/TransformerRegistry.java
+++ b/src/main/java/com/gtnewhorizons/postea/utility/TransformerRegistry.java
@@ -1,141 +1,93 @@
 package com.gtnewhorizons.postea.utility;
 
 import java.util.List;
-import java.util.Map;
+import java.util.function.BiFunction;
 import java.util.function.Function;
 
 import javax.annotation.Nullable;
 
 import net.minecraft.block.Block;
 import net.minecraft.item.Item;
-import net.minecraft.item.ItemBlock;
 import net.minecraft.nbt.NBTTagCompound;
 import net.minecraft.world.World;
-import net.minecraftforge.oredict.OreDictionary;
 
 import org.apache.commons.lang3.tuple.Pair;
 
 import com.google.common.collect.LinkedListMultimap;
 import com.gtnewhorizons.postea.api.IDExtenderCompat;
 
-import cpw.mods.fml.common.event.FMLModIdMappingEvent;
-import it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap;
 import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
 import it.unimi.dsi.fastutil.ints.IntOpenHashSet;
 
+/**
+ * A registry for all transformer functions
+ */
 public class TransformerRegistry {
 
-    private static final LinkedListMultimap<String, Function<NBTTagCompound, Boolean>> ITEM_REPLACEMENT_MAP = LinkedListMultimap
+    private static final LinkedListMultimap<String, BiFunction<String, NBTTagCompound, Boolean>> ITEM_REPLACEMENT_MAP = LinkedListMultimap
         .create();
     public static final LinkedListMultimap<String, Function<BlockConversionInfo, Boolean>> BLOCK_REPLACEMENT_MAP = LinkedListMultimap
         .create();
 
-    private static final Int2ObjectOpenHashMap<Pair<String, List<Function<NBTTagCompound, Boolean>>>> RUNTIME_ITEM_REPLACEMENT_MAP = new Int2ObjectOpenHashMap<>();
+    /**
+     * Map of itemID -> originalName+transformationHandler.
+     * Pivoting on the id is faster than pivoting on the strings so this should help with perf a bit.
+     * Generated during the mapping update event whilst entering/loading a world.
+     */
+    private static final Int2ObjectOpenHashMap<Pair<String, List<BiFunction<String, NBTTagCompound, Boolean>>>> RUNTIME_ITEM_REPLACEMENT_MAP = new Int2ObjectOpenHashMap<>();
+    /**
+     * Map of blockIO -> originalName+transformationHandler.
+     * Pivoting on the id is faster than pivoting on the strings so this should help with perf a bit.
+     * Generated during the mapping update event whilst entering/loading a world.
+     */
     private static final Int2ObjectOpenHashMap<Pair<String, List<Function<BlockConversionInfo, Boolean>>>> RUNTIME_BLOCK_REPLACEMENT_MAP = new Int2ObjectOpenHashMap<>();
-    private static final IntOpenHashSet DUMMY_IDS = new IntOpenHashSet();
     /**
-     * Map of IDs that were remapped by forge in the currently loaded save file. (usually happens due to missing
-     * mappings)
-     * Should be faster than asking block.getIdFromBlock() and Item.getIdFromItem()
+     * List of ids used by dummy items and blocks generated by Postea.
+     * Generated during the mapping update event whilst entering/loading a world.
      */
-    public static final Int2IntOpenHashMap REMAPPED_IDS = new Int2IntOpenHashMap();
+    public static final IntOpenHashSet DUMMY_IDS = new IntOpenHashSet();
 
     /**
-     * Stores simple item transformations (eg if old id is # with meta # then turn into item with id # with meta #.)
+     * Registers a block transformation handler function for the given id.
+     *
+     * @implNote It doesn't matter if the id doesn't belong to an existing block, a dummy block will be created when
+     *           Postea detects that the id isn't associated to a block during the FMLLoadCompleted event. Dependent
+     *           mods don't need to worry about this as the block name in the BlockConversionInfo is automatically
+     *           updated to the original id when attempting to transform a dummy block. When Postea runs a
+     *           transformation on a dummy block and no handler return true, Postea will automatically convert it to
+     *           air.
+     *
+     * @param originalId  The namespaced id of the block to transform.
+     * @param transformer The transformation handler that will execute a transformation on the block.
      */
-    public static final SimpleTransformationMap<Pair<Integer, Short>> SIMPLE_ITEM_TRANSFORMATION_MAP = new SimpleTransformationMap<>();
-    /**
-     * Stores simple block transformations (eg if old id is # with meta # then turn into item with id # with meta #.)
-     */
-    public static final SimpleTransformationMap<Pair<Integer, Short>> SIMPLE_BLOCK_TRANSFORMATION_MAP = new SimpleTransformationMap<>();
-
     public static void addBlockReplacement(String originalId, Function<BlockConversionInfo, Boolean> transformer) {
         MissingMappingHandler.createDummyBlockIfNeeded(originalId);
         BLOCK_REPLACEMENT_MAP.put(originalId, transformer);
     }
 
-    public static void addItemReplacement(String originalId, Function<NBTTagCompound, Boolean> transformer) {
+    /**
+     * Registers an item transformation handler function for the given id.
+     *
+     * @implNote It doesn't matter if the id doesn't belong to an existing item, a dummy item will be created when
+     *           Postea detects that the id isn't associated to an item during the FMLLoadCompleted event. Dependent
+     *           mods don't need to worry about this as transformation handlers are given the original id associated
+     *           with the nbt they are provided when the handler is executed. When Postea runs a transformation on a
+     *           dummy item and no handler returns true, Postea will automatically invalidate the stack by removing
+     *           its id and idExt fields.
+     *
+     * @param originalId  The namespaced id of the block to transform.
+     * @param transformer The transformation handler that will execute a transformation on the block.
+     */
+    public static void addItemReplacement(String originalId, BiFunction<String, NBTTagCompound, Boolean> transformer) {
         MissingMappingHandler.createDummyItemIfNeeded(originalId);
         ITEM_REPLACEMENT_MAP.put(originalId, transformer);
     }
 
-    public static void addSimpleTransformer(String originalId, int originalMeta, Block newBlock, int newMeta,
-        boolean skipStackRemap) {
-        if (newMeta == -1) newMeta = OreDictionary.WILDCARD_VALUE;
-        SIMPLE_BLOCK_TRANSFORMATION_MAP
-            .put(originalId, originalMeta, Pair.of(Block.getIdFromBlock(newBlock), (short) newMeta));
-        if (!skipStackRemap) {
-            Item item = Item.getItemFromBlock(newBlock);
-            if (item != null) {
-                SIMPLE_ITEM_TRANSFORMATION_MAP
-                    .put(originalId, originalMeta, Pair.of(Item.getIdFromItem(item), (short) newMeta));
-            }
-        }
-    }
-
-    public static void addSimpleTransformer(String originalId, int originalMeta, Item newItem, int newMeta,
-        boolean skipBlockRemap) {
-        if (newMeta == -1) newMeta = OreDictionary.WILDCARD_VALUE;
-        if (!skipBlockRemap && newItem instanceof ItemBlock ib) {
-            SIMPLE_BLOCK_TRANSFORMATION_MAP
-                .put(originalId, originalMeta, Pair.of(Block.getIdFromBlock(ib.field_150939_a), (short) newMeta));
-        }
-        SIMPLE_ITEM_TRANSFORMATION_MAP
-            .put(originalId, originalMeta, Pair.of(Item.getIdFromItem(newItem), (short) newMeta));
-    }
-
-    private static boolean simpleBlockTransformer(BlockConversionInfo info,
-        Map<Integer, Pair<Integer, Short>> metaMap) {
-        Pair<Integer, Short> mapping = SimpleTransformationMap.getFromSubmap(metaMap, info.metadata);
-        if (mapping == null) return false;
-        int key = mapping.getKey();
-        info.blockID = REMAPPED_IDS.getOrDefault(key, key);
-        if (mapping.getValue() != OreDictionary.WILDCARD_VALUE) {
-            info.metadata = mapping.getValue();
-        }
-        return true;
-    }
-
-    private static boolean simpleItemStackTransformer(NBTTagCompound tag, Map<Integer, Pair<Integer, Short>> metaMap) {
-        short meta = tag.getShort("Damage");
-        Pair<Integer, Short> mapping = SimpleTransformationMap.getFromSubmap(metaMap, meta);
-        if (mapping == null) return false;
-        int key = mapping.getKey();
-        IDExtenderCompat.setItemStackID(tag, REMAPPED_IDS.getOrDefault(key, key));
-        if (mapping.getValue() != OreDictionary.WILDCARD_VALUE) {
-            tag.setShort("Damage", mapping.getValue());
-        }
-        return true;
-    }
-
-    public static boolean isDummyId(int id) {
-        return DUMMY_IDS.contains(id);
-    }
-
     // region FML Life Cycle handlers
-    public static void onLoadCompleted() {
-        // add handlers for simple block remaps
-        for (Map.Entry<String, Map<Integer, Pair<Integer, Short>>> kv : SIMPLE_BLOCK_TRANSFORMATION_MAP.entrySet()) {
-            MissingMappingHandler.createDummyBlockIfNeeded(kv.getKey());
-            BLOCK_REPLACEMENT_MAP.put(kv.getKey(), info -> simpleBlockTransformer(info, kv.getValue()));
-        }
-        // add handlers for simple item remaps
-        for (Map.Entry<String, Map<Integer, Pair<Integer, Short>>> kv : SIMPLE_ITEM_TRANSFORMATION_MAP.entrySet()) {
-            MissingMappingHandler.createDummyItemIfNeeded(kv.getKey());
-            ITEM_REPLACEMENT_MAP.put(kv.getKey(), tag -> simpleItemStackTransformer(tag, kv.getValue()));
-        }
-    }
-
-    public static void onIdMappingsChanged(FMLModIdMappingEvent event) {
-        REMAPPED_IDS.clear();
+    public static void onIdMappingsChanged() {
         DUMMY_IDS.clear();
         RUNTIME_BLOCK_REPLACEMENT_MAP.clear();
         RUNTIME_ITEM_REPLACEMENT_MAP.clear();
-        // Store the remapped ids since the simple transform pivot on ids since it's faster using the block/item.
-        for (FMLModIdMappingEvent.ModRemapping remap : event.remappedIds) {
-            // the remapping type doesn't actually matter, FML doesn't seem to handle it right anyway.
-            REMAPPED_IDS.putIfAbsent(remap.oldId, remap.newId);
-        }
         // create a lookup for source block ids.
         for (String key : BLOCK_REPLACEMENT_MAP.keys()) {
             String name = MissingMappingHandler.getDummyIdIfMissing(key);
@@ -161,12 +113,15 @@ public class TransformerRegistry {
     public static void onServerStopping() {
         RUNTIME_BLOCK_REPLACEMENT_MAP.clear();
         RUNTIME_ITEM_REPLACEMENT_MAP.clear();
-        REMAPPED_IDS.clear();
         DUMMY_IDS.clear();
     }
     // endregion FML Life Cycle handlers
 
-    // region block replacement handler
+    // region transformation handlers
+    public static boolean isDummyId(int id) {
+        return TransformerRegistry.DUMMY_IDS.contains(id);
+    }
+
     public static @Nullable BlockConversionInfo getBlockReplacement(int blockId, byte metadata, World world, int x,
         int y, int z) {
         Pair<String, List<Function<BlockConversionInfo, Boolean>>> data = RUNTIME_BLOCK_REPLACEMENT_MAP.get(blockId);
@@ -197,22 +152,20 @@ public class TransformerRegistry {
         }
         return null;
     }
-    // endregion block replacement handler
 
-    // region item replacement handler
     public static void transformItem(NBTTagCompound tag) {
         // abort early if tag is bad.
         if (tag.hasNoTags() || !tag.hasKey("id")) return;
         // get handler
         int id = IDExtenderCompat.getItemStackID(tag);
-        Pair<String, List<Function<NBTTagCompound, Boolean>>> data = RUNTIME_ITEM_REPLACEMENT_MAP.get(id);
+        Pair<String, List<BiFunction<String, NBTTagCompound, Boolean>>> data = RUNTIME_ITEM_REPLACEMENT_MAP.get(id);
         // abort early if handler not found
         if (data == null || data.getValue()
             .isEmpty()) return;
 
         // apply handlers
-        for (Function<NBTTagCompound, Boolean> transformer : data.getValue()) {
-            if (transformer.apply(tag)) {
+        for (BiFunction<String, NBTTagCompound, Boolean> transformer : data.getValue()) {
+            if (transformer.apply(data.getKey(), tag)) {
                 // Not sure if we want to keep this around since this would affect perf a bit, good for debugging
                 // though.
                 // if (DUMMY_IDS.contains(IDExtenderCompat.getItemStackID(tag))) FMLLog.warning("returned a success on a
@@ -226,15 +179,5 @@ public class TransformerRegistry {
             tag.removeTag("idExt");
         }
     }
-
-    /**
-     * A method to go from tag -> name since that's not provided to handlers usually.
-     * Could be useful if you have one handler function handling a lot of complex transforms.
-     */
-    public static @Nullable String getMappedItemName(int itemId) {
-        Pair<String, List<Function<NBTTagCompound, Boolean>>> data = RUNTIME_ITEM_REPLACEMENT_MAP.get(itemId);
-        if (data == null) return null;
-        return data.getKey();
-    }
-    // endregion item replacement handler
+    // endregion transformation handlers
 }