Rounds 16-18 — native scroll (Lenis out), raster diet, scroll-frozen audio cosmetics#29
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…cs (rounds 16-18) Round 16 — scroll refonte (researched + measured) : - Lenis REMOVED -> native scrolling. Its permanent rAF re-dispatched scroll through the main thread (jank-amplifier) and the ~1 s easing was the reported 'floaty/slow' feel. 2026 consensus (NN/g, Thought- works radar, Apple's own product pages) : native scroll + sticky + pre-rendered frames. Anchors/tour keep a glide via CSS scroll-behavior: smooth (reduced-motion gated) ; the tour's manual rAF glide now passes behavior:'instant' to avoid double-easing. - dead useScrollProgress hooks removed (their only CSS consumer was deleted in round 12 — a forced layout per frame for nothing) - useScrollParallax: permanent rAF -> scroll-event driven - useAudioParticles: IntersectionObserver gate + 30 Hz - hero backdrop pre-blurred offline (npm run generate:backdrop, sharp: svg -> 640px -> sigma28 + saturate/brightness baked -> webp 4.5 kB) — retires the page's costliest live filter layer (blur(110px) on a viewport-sized surface). gitignore exception for the 2 derived webp (MIT svg sources, full rights chain). Round 17 — reveal raster diet : - 7 filter:blur(20-60px) removed from gradient-only glow layers (a radial gradient fading to transparent is already soft) ; worst was the halo MOVING with the scrub-tweened product every frame. Screenshot pairs: visually indistinguishable. Reveal flick p95 49.9 -> 33.7 ms. A velocity-gate on act swaps was tested, measured inconclusive (machine variance +/-10pts), and REVERTED. Round 18 — pause/playing parity : - new useScrollActivity singleton (one passive listener, 160 ms settle) ; ambient pump (now 30 Hz), AudioBars canvas and particle field FREEZE while the page scrolls — a frozen canvas scrolls as a cached texture, and mid-scroll screenshots show the frozen pose is imperceptible. Same-run differential: scroll jank delta paused->playing +21pts -> +8pts ; idle parity. Validation : ci exit=0 (88 tests, 0 vulns, lib byte-identical v2.3.5 untouched), visual 2/2, responsive 6/6, Axe AA 2/2, dist verified (no lenis in bundle, baked backdrops present). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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What
scroll-behavior: smoothfor anchors/tour (reduced-motion gated), tour glide fixed tobehavior:'instant'.npm run generate:backdrop), 7 gradient-layer blurs removed from the pinned reveal (screenshot pairs: indistinguishable), dead per-frame hooks removed, parallax event-driven, particles IO+30 Hz.useScrollActivitysingleton freezes ambient pump + AudioBars + particles while the page scrolls. Same-run differential: scroll jank delta paused→playing +21pts → +8pts, idle parity.Numbers (2K, headed GPU, same-run differentials)
idle paused/playing 0 %/0 % · read-pace full page paused 8 % · reveal flick p95 49.9 → 33.7 ms · input latency: native (was ~1 s Lenis easing)
Validation
ci exit=0 (88 tests, 0 vulns, src/lib untouched — byte-identical v2.3.5 ✓) · visual 2/2 · responsive 6/6 · Axe AA 2/2 · dist verified (no lenis, backdrops present) · an unproven micro-optimisation was tested and reverted (measurement honesty)
🤖 Generated with Claude Code