Performance and accessibility audit (Lighthouse)

Measured 2026-10-05 against the live site https://b3tl.loca.zone (D-322d T-39 and T-40, CHECKLIST 7.1 and 7.2).

• Tool: Lighthouse 13.5.0 with headless Chromium 151.0.0.0, the default mobile profile and simulate throttling.
• Routes: Home /, Playlists /playlists, Settings /settings and Analytics /analytics. Beetle has no separate player route: the player bar is part of the layout on every audited route.
• One run per route, so scores can move a few points between runs.
• Re-run one route: npx lighthouse@<version> https://b3tl.loca.zone/playlists --only-categories=performance,accessibility,best-practices --output=json --chrome-flags="--headless=new".

Scores

Route	Performance	Accessibility	Best practices	FCP	LCP	TBT	CLS	Speed index
Home /	59	100	100	1.7 s	3.0 s	7,560 ms	0.003	5.7 s
Playlists /playlists	37	100	100	1.7 s	3.6 s	3,010 ms	0.595	3.5 s
Settings /settings	61	100	100	1.3 s	3.5 s	2,380 ms	0	3.9 s
Analytics /analytics	66	100	100	2.4 s	2.7 s	1,620 ms	0	3.2 s

Asset loading review (CHECKLIST 7.2)

Lighthouse asset audits per route, scored out of 100 (90 or more passes). Render-blocking shows the earlier run (before T-55) → this run.

Route	Render-blocking	Caching	Document latency	Fonts	Images	Unused JS	Unused CSS	Legacy JS	Duplicated JS	Byte weight
Home /	50 → 0	100	100	100	100	100	100	100	100	100
Playlists /playlists	50 → 50	100	100	100	100	100	100	100	100	100
Settings /settings	100 → 100	100	100	100	100	100	100	100	100	100
Analytics /analytics	50 → 50	100	100	100	100	100	100	100	100	100

• Home render-blocking resources: 0.DObPAwY7.css (26194 B), StarRating.BOn_jhNY.css (335 B).
• Playlists render-blocking resources: StarRating.BOn_jhNY.css (335 B), 0.DObPAwY7.css (26194 B).
• Analytics render-blocking resources: 3.eD5b1AjY.css (266 B), StarRating.BOn_jhNY.css (335 B), 0.DObPAwY7.css (26194 B).
• Render-blocking CSS is the one partial result. Removing it means inlining the app CSS into every server-rendered response (kit.inlineStyleThreshold), which gives up CSS caching for full page loads. D-322d tried that (3233a0d) and reverted it (eb1cd1a): the trade-off is the owner’s call, and the timing-sensitive playback smoke ran slower with it on the overloaded host.
• Not an asset problem: Lighthouse attributes most main-thread time on / to https://b3tl.loca.zone/ (9,514 ms total, 306 ms scripting), which is rendering the server-rendered first page rather than loading assets.

Audits scoring below 90

Scored audits only (informative, manual and not-applicable audits are left out), lowest first.

Home /

• total-blocking-time Total Blocking Time: 7,560 ms (score 0)
• max-potential-fid Max Potential First Input Delay: 1,560 ms (score 0)
• mainthread-work-breakdown Minimize main-thread work: 15.6 s (score 0)
• bootup-time Reduce JavaScript execution time: 2.7 s (score 0)
• forced-reflow-insight Forced reflow (score 0)
• network-dependency-tree-insight Network dependency tree (score 0)
• render-blocking-insight Render-blocking requests: Est savings of 210 ms (score 0)
• interactive Time to Interactive: 10.6 s (score 23)
• speed-index Speed Index: 5.7 s (score 50)
• largest-contentful-paint Largest Contentful Paint: 3.0 s (score 78)

Playlists /playlists

• max-potential-fid Max Potential First Input Delay: 910 ms (score 0)
• mainthread-work-breakdown Minimize main-thread work: 8.3 s (score 0)
• bootup-time Reduce JavaScript execution time: 2.0 s (score 0)
• layout-shifts Avoid large layout shifts: 1 layout shift found (score 0)
• cls-culprits-insight Layout shift culprits (score 0)
• forced-reflow-insight Forced reflow (score 0)
• lcp-breakdown-insight LCP breakdown (score 0)
• network-dependency-tree-insight Network dependency tree (score 0)
• total-blocking-time Total Blocking Time: 3,010 ms (score 2)
• cumulative-layout-shift Cumulative Layout Shift: 0.595 (score 11)
• render-blocking-insight Render-blocking requests (score 50)
• largest-contentful-paint Largest Contentful Paint: 3.6 s (score 62)
• interactive Time to Interactive: 5.5 s (score 70)
• speed-index Speed Index: 3.5 s (score 88)

Settings /settings

• max-potential-fid Max Potential First Input Delay: 1,600 ms (score 0)
• mainthread-work-breakdown Minimize main-thread work: 6.2 s (score 0)
• bootup-time Reduce JavaScript execution time: 1.6 s (score 0)
• forced-reflow-insight Forced reflow (score 0)
• network-dependency-tree-insight Network dependency tree (score 0)
• total-blocking-time Total Blocking Time: 2,380 ms (score 5)
• largest-contentful-paint Largest Contentful Paint: 3.5 s (score 64)
• speed-index Speed Index: 3.9 s (score 82)
• interactive Time to Interactive: 4.2 s (score 86)

Analytics /analytics

• max-potential-fid Max Potential First Input Delay: 1,220 ms (score 0)
• mainthread-work-breakdown Minimize main-thread work: 6.3 s (score 0)
• bootup-time Reduce JavaScript execution time: 1.7 s (score 0)
• network-dependency-tree-insight Network dependency tree (score 0)
• total-blocking-time Total Blocking Time: 1,620 ms (score 12)
• render-blocking-insight Render-blocking requests (score 50)
• first-contentful-paint First Contentful Paint: 2.4 s (score 71)
• interactive Time to Interactive: 4.6 s (score 81)
• largest-contentful-paint Largest Contentful Paint: 2.7 s (score 85)