Perf: defer third party widgets#1045
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Both Senja embeds rendered below the fold but fetched their loader scripts eagerly on page parse — ~430 KB and ~1.5 s of JS plus a render-blocking Google Fonts (Inter) request on the initial path. Move each loader URL onto a `data-senja-src` attribute and inject it via a shared IntersectionObserver (200px rootMargin), mirroring the lazy feature-video pattern in Feature.astro. Reserve min-height on each embed so the late-loading widget does not shift content (CLS stays ~0). Verified via Lighthouse: zero senja.io / google-fonts requests on initial load; CLS ~0. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Replace Intercom's window.load trigger with a first-interaction trigger (scroll/mousemove/touchstart/keydown/click) plus a requestIdleCallback idle fallback (5s backstop), so the ~344KB widget no longer competes for network and main thread during the critical initial load. Passive readers still get the launcher via the idle fallback. Window-level guards (__intercomArmed/__intercomLoaded) keep it from double-loading across Astro view-transition navigations. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Why
Antoine reported the landing page felt slow — usable only once the Intercom bubble appeared. That's the tell: the page looks done fast but stays unresponsive while third-party scripts fire on
window.load.Findings (Lighthouse, mobile/throttled)
Page content is healthy; third-party is the cost. Speed Index 2.1 s but TTI 11.7 s — the "looks done but isn't" gap.
window.load— the worst moment for interactivity.Solution
fec0cdf): inject loaders via a sharedIntersectionObserver(200px margin) only as widgets near the viewport; reservemin-heightso CLS stays ~0.ac0d33a): replace thewindow.loadtrigger with first-interaction + arequestIdleCallbackidle fallback (5 s backstop). Passive readers still get the launcher via idle; window-level guards prevent double-loading across view transitions.Verification
senja.io/ Google-Fonts requests on initial load; CLS ~0.build,lint,format:check,typecheck,knipall pass.🤖 Generated with Claude Code