astro-website/review-notes.md

Performance Review — santhoshj.com

Date: 2026-04-11

Lighthouse Scores

Category	Desktop	Mobile
Performance	100	95
Accessibility	100	100
Best Practices	100	100
SEO	100	100

Core Web Vitals

Metric	Desktop	Mobile	Rating
FCP	0.4s	2.3s	Desktop: Great / Mobile: Needs improvement
LCP	0.6s	2.4s	Desktop: Great / Mobile: Good
TBT	0ms	0ms	Great
CLS	0.001	0.001	Great
SI	0.5s	2.4s	Desktop: Great / Mobile: Great
TTI	0.6s	2.4s	Desktop: Great / Mobile: Great

LCP element: H1 text node (no image resource).

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Actionable Items (Priority Order)

1. Fix forced reflow — 48ms waste

• setOpen() at index.html:502 causes 47ms forced sync layout
• updateNotchTop() at index.html:623 also triggers reflow
• Root cause: reads geometric properties (e.g. offsetWidth) after DOM writes
• Fix: batch all layout reads before writes, or wrap writes in requestAnimationFrame

2. Add cache headers to JS bundles

• Astro-hashed JS assets served with cache-control TTL=0
• These files have content hashes in filenames — safe to cache long-term
• Fix: set cache-control: public, max-age=31536000, immutable on /_astro/* and other hashed assets
• Location: nginx config or CDN cache policy

3. Remove cache-control: no-store from HTML

• Current: HTML doc uses no-store → back/forward cache disabled
• Prevents instant back navigation (bfcache)
• Fix: replace no-store with cache-control: max-age=0, must-revalidate
• Also affects JS network requests receiving no-store resources

4. Tree-shake unused CSS — 30KB waste

• Two CSS chunks (16KB + 14KB) are entirely unused on the homepage
• Likely page-specific styles loaded eagerly
• Fix: ensure Astro code-splitting for CSS per page, or remove unused selectors
• Check /_astro/_slug_.*.css — may bundle all page styles into one sheet

5. Defer render-blocking JS — 550ms mobile waste

• Main JS bundle and CSS are render-blocking
• Fix: inline critical JS/CSS, defer remaining with async or defer
• Or: use <link rel="preload"> for critical resources + defer for non-critical

6. Reduce unused JavaScript — 38KB / 99KB (38% waste)

• Main Astro JS bundle: 38KB unused out of 99KB
• Fix: audit Astro client-side scripts, remove unused island code, or split into smaller chunks
• Check if setOpen, updateNotchTop, umami analytics, and other inline scripts can be deferred

7. Optimize image delivery — 323KB mobile savings

• YouTube thumbnails served as-is (JPEG, no WebP/AVIF)
• No responsive srcset — full-size thumbnails on all viewports
• Fix: use <picture> with WebP/AVIF fallback, add loading="lazy" for below-fold images, consider width/height attributes to reduce CLS risk
• Note: these are 3rd-party ytimg.com URLs — limited control. Consider proxying or using YouTube's mqdefault.jpg (smaller) for mobile