small optimizations

src/FakeShader.ts

@@ -476,21 +476,36 @@ export class FakeShader {
     }
   }
 
-  private compositeTiles(): void {
-    const width = this.canvas.width;
+  private async compositeTiles(): Promise<void> {
     const height = this.canvas.height;
     const tileHeight = Math.ceil(height / this.workerCount);
 
-    // Clear main canvas
-    this.ctx.clearRect(0, 0, width, height);
-
-    // Composite all tiles directly on main canvas
-    for (let i = 0; i < this.workerCount; i++) {
-      const tileData = this.tileResults.get(i);
-      if (tileData) {
-        const startY = i * tileHeight;
-        this.ctx.putImageData(tileData, 0, startY);
+    // Use ImageBitmap for faster compositing if available
+    if (typeof createImageBitmap !== 'undefined') {
+      try {
+        const bitmapPromises: Promise<ImageBitmap>[] = [];
+        const positions: number[] = [];
+        
+        for (let i = 0; i < this.workerCount; i++) {
+          const tileData = this.tileResults.get(i);
+          if (tileData) {
+            bitmapPromises.push(createImageBitmap(tileData));
+            positions.push(i * tileHeight);
+          }
+        }
+        
+        const bitmaps = await Promise.all(bitmapPromises);
+        
+        for (let i = 0; i < bitmaps.length; i++) {
+          this.ctx.drawImage(bitmaps[i], 0, positions[i]);
+          bitmaps[i].close(); // Free memory
+        }
+      } catch (error) {
+        // Fallback to putImageData if ImageBitmap fails
+        this.fallbackCompositeTiles();
       }
+    } else {
+      this.fallbackCompositeTiles();
     }
 
     // Clear tile results
@@ -510,6 +525,18 @@ export class FakeShader {
     }
   }
 
+  private fallbackCompositeTiles(): void {
+    const tileHeight = Math.ceil(this.canvas.height / this.workerCount);
+    
+    for (let i = 0; i < this.workerCount; i++) {
+      const tileData = this.tileResults.get(i);
+      if (tileData) {
+        const startY = i * tileHeight;
+        this.ctx.putImageData(tileData, 0, startY);
+      }
+    }
+  }
+
   // Simplified method - kept for backward compatibility but always uses all cores
   setMultiWorkerMode(_enabled: boolean, _workerCount?: number): void {
     // Always use all available cores, ignore the enabled parameter