Improve WebGPU setting

bench/README.md

@@ -105,6 +105,20 @@ bench/
 └── vite.config.ts
 ```
 
+## ⚠️ Important: WebGPU Headless Limitations
+
+**WebGPU performance in headless mode is significantly degraded** (~25× slower than headed mode on macOS). This is a known limitation of headless browsers:
+
+- **Headless mode**: Uses software rendering, giving misleading results
+- **Headed mode** (`--headed=true`): Uses actual GPU, reflects real performance
+- **Interactive UI** (`npm run dev`): Best for accurate WebGPU benchmarks
+
+**Recommendation**: For WebGPU benchmarks, always use `--headed=true` or test interactively in a browser.
+
+See: [Chrome WebGPU Testing Guide](https://developer.chrome.com/blog/supercharge-web-ai-testing#enable-webgpu) | [Playwright GPU Issues](https://github.com/microsoft/playwright/issues/11627)
+
+---
+
 ## Output Format
 
 All benchmarks output JSON with the following structure:

bench/src/web/cli.ts

@@ -43,11 +43,30 @@ async function main() {
   console.log(`Vite server started at ${url}`);
 
   let browser: Browser;
+
+  // Build args based on mode
+  const args = device === "wasm"
+    ? ["--disable-gpu", "--disable-software-rasterizer"]
+    : [
+        // Official WebGPU flags from Chrome team
+        // https://developer.chrome.com/blog/supercharge-web-ai-testing#enable-webgpu
+        "--enable-unsafe-webgpu",
+        "--enable-features=Vulkan",
+      ];
+
+  // Add headless-specific flags only in headless mode
+  if (!headed && device !== "wasm") {
+    args.push(
+      "--no-sandbox",
+      "--headless=new",
+      "--use-angle=vulkan",
+      "--disable-vulkan-surface"
+    );
+  }
+
   const launchOptions = {
     headless: !headed,
-    args: device === "wasm"
-      ? ["--disable-gpu", "--disable-software-rasterizer"]
-      : ["--enable-unsafe-webgpu", "--enable-features=Vulkan"]
+    args,
   };
 
   switch (browserType) {