Skip quiet block update checks

- ChunkBlockUpdateListener remembers the last state with no update or custom effect
- Plain terrain runs skip the per-block isUpdatable and isCustom checks
- Test replays random writes against the per-write catch semantics

core/src/main/java/art/arcane/iris/generation/runtime/ChunkBlockUpdateListener.java

@@ -0,0 +1,53 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2026 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package art.arcane.iris.generation.runtime;
+
+import art.arcane.iris.generation.block.B;
+import art.arcane.iris.generation.chunk.ColumnExtentListeningHunk;
+import art.arcane.volmlib.nativelib.terrain.NativeBlockState;
+
+/**
+ * Forwards a chunk's block writes to {@link BlockUpdater#catchBlockUpdates} at world coordinates.
+ * The last state seen to need neither a block update nor custom handling is remembered, so the
+ * long runs of plain terrain skip the per-block checks. Racing writers only ever store such states.
+ */
+final class ChunkBlockUpdateListener implements ColumnExtentListeningHunk.Listener<NativeBlockState> {
+    private final BlockUpdater updater;
+    private final int originX;
+    private final int originZ;
+    private NativeBlockState quiet;
+
+    ChunkBlockUpdateListener(BlockUpdater updater, int originX, int originZ) {
+        this.updater = updater;
+        this.originX = originX;
+        this.originZ = originZ;
+    }
+
+    @Override
+    public void onWrite(int x, int y, int z, NativeBlockState state) {
+        if (state == null || state == quiet) {
+            return;
+        }
+        if (B.isUpdatable(state) || state.isCustom()) {
+            updater.catchBlockUpdates(originX + x, y, originZ + z, state);
+            return;
+        }
+        quiet = state;
+    }
+}

core/src/main/java/art/arcane/iris/generation/runtime/IrisEngine.java

@@ -1472,7 +1472,7 @@ public class IrisEngine implements Engine {
              IrisContext.Scope generationScope = IrisContext.open(this, lease.sessionId(), null)) {
             getEngineData().getStatistics().generatedChunk();
             PrecisionStopwatch p = PrecisionStopwatch.start();
-            Hunk<NativeBlockState> blocks = new ColumnExtentListeningHunk<>(vblocks, (xx, y, zz, t) -> catchBlockUpdates(x + xx, y, z + zz, t));
+            Hunk<NativeBlockState> blocks = new ColumnExtentListeningHunk<>(vblocks, new ChunkBlockUpdateListener(this, x, z));
 
             if (getDimension().isDebugChunkCrossSections() && ((x >> 4) % getDimension().getDebugCrossSectionsMod() == 0 || (z >> 4) % getDimension().getDebugCrossSectionsMod() == 0)) {
                 NativeBlockState crossSection = B.getState("CRYING_OBSIDIAN");