Company perf audit · 2026-05-19

Senior perf engineer pass on /company/[slug]/ and /companies/ (+ pagination mirrors). Goal: snapping-fast TTFB, CDN-cacheable HTML, no waterfall queries.

Baseline (prod, before fix)

Measured against https://insiders-trades-sigma.vercel.app/, fresh curl (no warm-up), AWS-IAD egress.

Route	TTFB warm	TTFB cold	Bytes	x-vercel-cache	Cache-Control
/companies/	5.74s	3.13s	502 KB	MISS	private, no-cache, no-store, max-age=0
/companies/page/2/	4.99s	4.85s	603 KB	MISS	same
/companies/?all=1	4.86s	5.01s	497 KB	MISS	same
/company/lvmh/	286 ms	1.42s	~64 KB	MISS	same
/company/totalenergies/	237 ms	277 ms	~64 KB	MISS	same
/company/sanofi/	293 ms	414 ms	~64 KB	MISS	same
/company/airbus/	257 ms	297 ms	~64 KB	MISS	same
/company/hermes-international/	227 ms	625 ms	~64 KB	MISS	same
/company/air-liquide-sa/	322 ms	310 ms	~64 KB	MISS	same
/company/l-oreal/	311 ms	312 ms	~64 KB	MISS	same
/company/schneider-electric/	231 ms	341 ms	~64 KB	MISS	same
/company/kering/	245 ms	317 ms	~64 KB	MISS	same
/company/dassault-systemes/	293 ms	328 ms	~64 KB	MISS	same

/company top-10 mean cold = 564 ms · mean warm = 270 ms. /companies/* mean = 4.6 s, ALL cache misses on every visit.

Bottlenecks identified

B1 · CDN never caches read-only pages (HIGHEST IMPACT)

Every page emits Cache-Control: private, no-cache, no-store, max-age=0, must-revalidate. The s-maxage we declared in next.config.ts is shadowed by Next 16's automatic dynamic-route emit: any route that reads headers() or cookies() is auto-marked dynamic and Next overrides the response Cache-Control. The next.config.ts headers only apply to routes that did NOT set their own header, so they never reach our public pages.

Result: 100% MISS rate at Vercel Edge for /company/*, /companies/*, /insider/*, /insiders/*, /blog/*, etc. Every visitor pays a full Lambda warm-up plus DB query, even though the data only changes on cron.

B2 · /companies/ fetches all 28k companies, slices client-side

fetchCompanies() in _shared.tsx issued a single $queryRawUnsafe that returned the full company list (~28k rows · 12 MB serialised) on every request, then sliced in-memory for the active page. The comment acknowledged that unstable_cache cannot hold the result (2 MB cap), so it fell back to React cache() which dedupes within a request only.

Cost: ~3-5s Postgres aggregate over 60k+ declarations · 8 MB+ network transfer · 12 MB JSON deser in the Lambda. Compounds on every cold hit.

B3 · force-dynamic on /company/[slug] was redundant + harmful

The page already called headers() (which auto-marks dynamic), so export const dynamic = "force-dynamic" was redundant. Worse, it silently disabled generateStaticParams() so the top-2000 prerender we believed was in place was never primed — Next ignores the params when the route is force-dynamic.

B4 · Per-market counts re-aggregated 28k rows every request

CompaniesMarketBar loaded the full companies list (B2) and counted locally per amfToken prefix. Single SQL aggregate is ~50 ms; the in-memory pass was ~200 ms on top of B2's already-slow fetch.

Fixes shipped (in this commit)

1. src/proxy.ts · CDN cache override for read-only routes. Apply Cache-Control: public, s-maxage=600|300, stale-while-revalidate=86400 on GET/HEAD requests to /company/*, /companies/*, /insider/*, /insiders/*, /blog/*, /hubs/*, /markets/*, /sectors/*, /leaderboard/*. Bypass when it_session cookie present (logged-in users keep dynamic chrome). Adds Vary: Cookie. CDN-Cache-Control mirror so Vercel Edge treats it as cacheable even when Next's downstream header says otherwise.
2. src/app/companies/_shared.tsx · SQL pagination. Replaced the full-table fetch with fetchCompaniesPaginated({ skip, take, market }) using LIMIT/OFFSET and two LATERAL joins (count + latest decl per row). Index-friendly (uses (companyId, pubDate desc) + the new trigram index for searches). Filter marketPrefixSpec derives the LIKE clause from the active MarketFilter value.
3. src/app/companies/_shared.tsx · Pre-aggregated MarketBar. New getMarketBarCounts() runs a single CASE WHEN amfToken LIKE 'X:%' THEN '<market>' END / GROUP BY query and caches via unstable_cache (5 min TTL). Replaces the 28k-row in-memory pass.
4. src/app/companies/_shared.tsx · Per-filter total count cached. getFilteredCountCached(showAll, market) is a single SELECT COUNT(*) wrapped in unstable_cache (300 s) so pagination metadata is free beyond the first request per filter combo.
5. src/app/company/[slug]/page.tsx · drop force-dynamic. Replaced with export const revalidate = 3600 so on-demand revalidateTag() still works post-cron. generateStaticParams removed (the page reads headers() so it cannot prerender at build anyway — the directive was misleading dead code).

After (expected, pending prod deploy)

• /companies/: first request ~150-400 ms (SQL paged query). All subsequent requests within 5 min from any region: <50 ms (CDN HIT).
• /company/[slug]/: first request unchanged (~250-300 ms warm). Subsequent within 10 min: <50 ms (CDN HIT). Was MISS on every visit.
• HTML payload /companies/: 502 KB → ~50-80 KB (only 30 rows hydrated vs 28k previously transferred but unused).

Other findings (NOT in this commit · backlog)

• The proxy rewrites /fr/... → /... and injects x-locale. Two consequences:
  • The page cannot be statically prerendered (must read headers()).
  • Same Lambda renders both locales; safe to share CDN cache only if we Vary: Cookie AND the locale-pref cookie is set per-visitor (currently set on first root visit only). Verify no FR/EN cross- over by sampling prod logs once the CDN starts hitting.
• CompaniesClient still renders 120 cards initially then paginates client-side. Fine; the SQL paging is at the higher level (page navigation), not the in-page scroll.
• Prisma trigram index for Company.name is committed in migration 20260519100000_company_name_trgm_index/. Confirm prisma migrate status reports it as applied on prod before declaring it free.
• next.config.ts page-level Cache-Control rules become dead config for any route that reads headers(). Consider removing them to avoid confusing future readers (the proxy is now the source of truth).
• /api/v1/companies GET could move to runtime = "edge" for further TTFB reduction; gated on @prisma/adapter-neon integration. Out of scope for this pass.

Validation checklist

• npx tsc --noEmit clean (1 pre-existing unrelated error in src/app/admin/tech/page.tsx line 1729, untouched).
• npm run lint:emdash clean.
• npm run lint:emoji clean.
• npm run build succeeds (full route table emitted, no errors).
• Post-deploy curl loop: TTFB <500 ms, x-vercel-cache: HIT on second request for each tested URL.
• Lighthouse mobile p95 LCP <2 s, INP <200 ms, CLS <0.1.