Why Is Volume Shader Test Lagging?
Five common reasons Volume Shader Test runs slowly, and how to fix each — integrated GPU, hardware acceleration, thermal throttling, and more.
If Volume Shader BM Test is running at a fraction of the FPS you expected, it's almost always one of a handful of things. Go through the list below in order — most users find the fix in the first three items.
Quick answer
- The browser is using your integrated GPU instead of the dedicated one.
- Hardware acceleration is off in browser settings.
- You're in Heavy or Extreme on a device that should be in Light or Medium.
- Thermal throttling — laptop on battery, phone overheated.
- Another tab (video, Maps, WebGL ad) is competing for the GPU.
1. Wrong GPU is being used
On laptops with both integrated and dedicated graphics, Chrome / Edge / Firefox often default to the integrated GPU to save battery. Open chrome://gpu (or edge://gpu) and look at "GL_RENDERER". If it shows Intel UHD / Iris while your machine has an NVIDIA or AMD GPU, set the browser to prefer high performance in your OS graphics settings.
2. Hardware acceleration is disabled
In Chrome / Edge: Settings → System → "Use graphics acceleration when available". In Safari: there's no toggle, but make sure you're not in Private Browsing on some older macOS versions, which disables WebGL acceleration.
3. Test mode is too heavy
Heavy and Extreme run over a thousand shader iterations per pixel. Even high-end GPUs only see 30–60 FPS in Heavy. For a baseline, run Light first, then bump up. See the FPS result guide for expected ranges.
4. Thermal throttling
Plug laptops into power before a Heavy run — most thin-and-light laptops cap GPU clocks aggressively on battery. On phones, results halve once the chassis gets warm. The phone GPU test guide explains the Android and iOS quirks.
5. Background tabs stealing GPU
A YouTube video or Google Maps tab in another window will steal frame budget. Close them, reload Volume Shader BM and run again.
Still slow?
Make sure your GPU driver is current. Old drivers can drop WebGL 2 performance by 30–50% on the same hardware.
Re-run the test
After applying a fix, measure again to see the difference.
Run Volume Shader BM Test again →
