Add option to disable thread pool

common/src/main/java/org/embeddedt/modernfix/common/mixin/feature/cause_lag_by_disabling_threads/ChunkRenderDispatcherMixin.java

@@ -0,0 +1,28 @@
+package org.embeddedt.modernfix.common.mixin.feature.cause_lag_by_disabling_threads;
+
+import net.minecraft.client.renderer.chunk.ChunkRenderDispatcher;
+import org.embeddedt.modernfix.annotation.ClientOnlyMixin;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.ModifyArg;
+import org.spongepowered.asm.mixin.injection.ModifyVariable;
+
+import java.util.concurrent.Executor;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+
+@Mixin(ChunkRenderDispatcher.class)
+@ClientOnlyMixin
+public class ChunkRenderDispatcherMixin {
+    private static final Executor MFIX_CHUNK_BUILD_EXECUTOR = new ThreadPoolExecutor(1, computeNumThreads(), 0L, TimeUnit.SECONDS, new LinkedBlockingQueue<>());
+
+    private static int computeNumThreads() {
+       return Math.max(Math.min(Runtime.getRuntime().availableProcessors() / 4, 10), 1);
+    }
+
+    @ModifyVariable(method = "<init>*", at = @At("HEAD"), ordinal = 0, argsOnly = true)
+    private static Executor replaceExecutor(Executor old) {
+        return MFIX_CHUNK_BUILD_EXECUTOR;
+    }
+}

common/src/main/java/org/embeddedt/modernfix/common/mixin/feature/cause_lag_by_disabling_threads/UtilMixin.java

@@ -0,0 +1,16 @@
+package org.embeddedt.modernfix.common.mixin.feature.cause_lag_by_disabling_threads;
+
+import net.minecraft.Util;
+import org.embeddedt.modernfix.util.DirectExecutorService;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Mutable;
+import org.spongepowered.asm.mixin.Shadow;
+
+import java.util.concurrent.ExecutorService;
+
+@Mixin(Util.class)
+public class UtilMixin {
+    @Shadow @Final @Mutable
+    private static final ExecutorService BACKGROUND_EXECUTOR = new DirectExecutorService();
+}

common/src/main/java/org/embeddedt/modernfix/core/config/ModernFixEarlyConfig.java

@@ -166,6 +166,7 @@ public class ModernFixEarlyConfig {
             .put("mixin.feature.stalled_chunk_load_detection", false)
             .put("mixin.perf.blast_search_trees.force", false)
             .put("mixin.bugfix.restore_old_dragon_movement", false)
+            .put("mixin.feature.cause_lag_by_disabling_threads", false)
             .put("mixin.perf.clear_mixin_classinfo", false)
             .put("mixin.perf.deduplicate_climate_parameters", false)
             .put("mixin.bugfix.packet_leak", false)

common/src/main/java/org/embeddedt/modernfix/util/DirectExecutorService.java

@@ -0,0 +1,43 @@
+package org.embeddedt.modernfix.util;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+import java.util.concurrent.AbstractExecutorService;
+import java.util.concurrent.TimeUnit;
+
+public class DirectExecutorService extends AbstractExecutorService {
+    private boolean isShutdown;
+
+    @Override
+    public void shutdown() {
+        isShutdown = true;
+    }
+
+    @NotNull
+    @Override
+    public List<Runnable> shutdownNow() {
+        isShutdown = true;
+        return List.of();
+    }
+
+    @Override
+    public boolean isShutdown() {
+        return isShutdown;
+    }
+
+    @Override
+    public boolean isTerminated() {
+        return isShutdown;
+    }
+
+    @Override
+    public boolean awaitTermination(long timeout, @NotNull TimeUnit unit) throws InterruptedException {
+        return true;
+    }
+
+    @Override
+    public void execute(@NotNull Runnable command) {
+        command.run();
+    }
+}