Accessibility: the land that time to interactive forgot
summary
Claim: the browser builds a second structure—the accessibility tree—and its construction path materially drives perceived Time To Interactive, sometimes adding many seconds (demo page with ~6995 links causes an 8–10s lag). Evidence: different browser architectures—Chrome copies a cached tree into the application process and speeds screen-reader queries, Firefox proxies with intelligent caching but is switching to an accessibility cache flag in nightly builds, Safari’s out‑of‑process model performs well. Built artifacts: virtual buffer on Windows screen readers, rewritten Firefox accessibility engine; practical tools mentioned: NVDA, JAWS, VoiceOver, Narrator and a Lighthouse issue to track metrics.
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chapters (8)
- 0:00Start
- 3:19Paint
- 4:58Accessibility tree
- 5:15Semantics
- 11:47In process communication
- 17:05Safari
- 18:17Accessibility rendering path
- 21:22Virtual buffer
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