v147 · Performance APIs · Origin Trial

Style vs Layout Analyzer

Run one style-heavy workload and one layout-heavy workload, then compare the split timing fields when the origin trial is active or the combined fallback timing when it is not.

This page deliberately keeps style and layout workloads separate. If styleDuration and layoutDuration are unavailable, it reports that as an unsupported origin-trial state rather than pretending zeros are meaningful split data.

remediation guide

// High styleDuration: reduce selector complexity and style invalidation.
// High layoutDuration: batch DOM writes before geometry reads.
// High forcedStyleDuration or forcedLayoutDuration:
//   inspect entry.scripts[] and remove synchronous reads after writes.
// No split fields: use styleAndLayoutStart and scripts[].forcedStyleAndLayoutDuration
//   as the baseline fallback until the origin trial is enabled.

see also