Collect runtime performance metrics from headless Chrome using raw CDP Performance and Tracing domains
domain: chromedevtools.github.io · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Send Performance.enable to start metric collection, then Performance.getMetrics to read counters like JSHeapUsedSize, LayoutCount, and Timestamp
For finer-grained paint/layout/script timing, use Tracing.start with a trace config, drive the interaction, then Tracing.end and collect the dataCollected/tracingComplete events
Cross-check CDP-derived numbers against the page's own Navigation Timing / Performance API values obtained via Runtime.evaluate
In Puppeteer, get a CDPSession through the page/target's CDP session helper rather than reimplementing the WebSocket transport by hand
Call Performance.disable when finished measuring to avoid leaking listeners across repeated measurement runs in the same session
Known gotchas
Performance.getMetrics values are cumulative counters since Performance.enable, not deltas — snapshot and diff two readings to isolate one interaction's cost
Tracing.start/end can produce a very large event stream over the CDP connection; buffering an entire long trace in memory can exhaust memory in CI
Headless Chrome's compositing/GPU path can differ from headed mode, so headless performance numbers should be treated as relative comparisons, not absolute production numbers
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