> Canonical page: https://posttrainllm.com/artifacts/browser-webgpu-speedup

Browser performance artifact Report artifact 2026-09-02

# Browser WebGPU Training Speedup

The browser playground now has a retained, adapter-qualified performance win for one configuration. Two WASM and two WebGPU runs used the same Large preset, corpus, seed, and 20-step budget. This qualifies Large on the measured M5 Pro; the older Small/Medium/XL curve remains historical until separately reproduced.

- WebGPU
- WASM
- browser
- performance

## Headline Numbers

Evidence class applies to each value: measured = retained evaluation or runtime result; historical = recorded result not freshly reproduced; derived = calculated or decided from records; observed = current artifact state; not-measured = an explicit evidence gap.

WebGPU speedup

 10.67x measured · Large · Apple M5 Pro measured

Loss drift

 4.72% maximum across two paired comparisons measured

Hardware gate

 pass Apple · metal-3 · no fallback measured

## Competitive Context

**System**

**Metric**

**Score**

**Size / Class**

**Comparable?**

**Readout**

 posttrainllm WebGPU training step speedup 10.67x Large · d_model=192 · 20 steps Direct Median 137.1 ms/step across two WebGPU runs on the same Apple hardware and frozen inputs.

 posttrainllm WASM SIMD training step speedup 1.0x same browser model/config Direct Median 1462.5 ms/step across the two matching WASM runs.

 Native Mac runtimes browser training benchmark not measured MLX/Metal class Not comparable Native runtimes are the right competition for production throughput, but not for the browser-learning artifact.

Direct rows share this artifact's eval setup. Directional rows are useful market context but should not be read as leaderboard claims.

## Performance readout

**Variant**

**Result**

**Interpretation**

 WASM · Large 1462.5 ms/step median Two matching runs

 WebGPU · Large 137.1 ms/step median 10.67x measured speedup

 Final-loss drift 4.72% maximum Passes the frozen

## Release Blockers

## Evidence

- [Performance journey](https://posttrainllm.com/roadmap)
- [Performance docs](https://posttrainllm.com/docs/performance/performance/)
- [Playground](https://posttrainllm.com/playground)
- [Paired result JSON](https://github.com/PostTrainLLM/posttrainllm/blob/main/evals/verified-wins/webgpu-paired-result-v1.json)

## Next Release Action

Keep Large as the measured M5 Pro win; reproduce Small, Medium, and XL independently before promoting the historical curve.