Performance Regression Testing

Any change to the render pipeline must prove it does not increase capture time. The primary guard is serializeTimelineDirect.perf.browsertest.ts, which measures captureTimelineToDataUri end-to-end in multiple scenarios.

Quick Workflow

# Before making changes — record baseline numbers from the terminal output
cd elements
./scripts/browsertest packages/elements/src/preview/rendering/serializeTimelineDirect.perf.browsertest.ts

# Make your changes, then re-run
./scripts/browsertest packages/elements/src/preview/rendering/serializeTimelineDirect.perf.browsertest.ts

The test prints p50, p95, p99 for each scenario. A fix is acceptable if p95 does not regress. Copy the before/after numbers into the PR description as evidence.

What Each Scenario Tests