Make mixin.perf.thread_priorities limit background thread count as well

Author: embeddedt

common/src/main/java/org/embeddedt/modernfix/core/ModernFixMixinPlugin.java

@@ -87,9 +87,21 @@ public void run() {
                 t.setDaemon(true);
                 t.start();
             }
+
+            if (ModernFixPlatformHooks.INSTANCE.isClient() && ModernFixMixinPlugin.instance.isOptionEnabled("perf.thread_priorities.AdjustThreadCount")) {
+                computeBetterThreadCount();
+            }
         }
     }
 
+    private void computeBetterThreadCount() {
+        // Server thread + client thread + GC thread
+        int reservedCores = 3;
+        int availableBackgroundCores = Math.max(1, Runtime.getRuntime().availableProcessors() - reservedCores);
+        logger.info("Configuring Minecraft's max.bg.threads option with {} threads", availableBackgroundCores);
+        System.setProperty("max.bg.threads", String.valueOf(availableBackgroundCores));
+    }
+
 
     @Override
     public void onLoad(String mixinPackage) {