Why Performance Matters - JSConf Budapest 201
summary
Claim: perceived speed matters more than bytes or milliseconds, and a 20% rule (Weber‑Fechner) often determines whether users notice improvements. Cited numbers: Walmart 1s → 2% conversion lift, Financial Times losing up to ~8% with 3s slowdowns, Wikipedia 100ms → 617 reader‑years saved. Techniques and results: preemptive start (Houston reroute, iOS Safari preload, Uno preloading search API and building the D‑tree) and early completion (video chunk playback); still use async loads, service workers and resource hints to make these work.
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chapters (7)
- 0:00Start
- 0:27Conversions
- 5:17WEBER-FECHNER LAW
- 10:39ACTIVE PASSIVE
- 11:41PREEMPTIVE START
- 16:49EARLY COMPLETION
- 19:53ASYNC
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