Vercel Speed Audit Skill

Optimize Vercel build and deploy speed for any project. Run as a checklist when starting new projects or auditing existing ones.

When to Use

• New project setup — configure optimal defaults from day one
• Build times creeping up — audit and fix performance regressions
• Deploy queue bottlenecks — eliminate waiting on concurrent builds
• Production incidents — use instant rollback instead of waiting for a new build
• Cost optimization — balance speed vs spend on build infrastructure

Triage First (Don't Blindly Run All 10)

Before running the full checklist, measure and assess:

# 1. Check current build times
cd <project> && npx vercel ls --limit 5

# 2. Check team/plan tier
npx vercel team ls

Decision tree:

Build Time	Action
< 20s	Only do items 0, 1, 3-5, 10. Skip GitHub Actions (#8), skip barrel file audit (#6) unless codebase is large.
20-60s	Do items 0-7, 10. GitHub Actions (#8) is optional.
60s+	Do everything. GitHub Actions (#8) becomes high-value.

Auth-gated app? (All pages behind login) → Skip ISR (#9) entirely. ISR caches one response for all users — incompatible with per-user content.

Framework: → SvelteKit: Also read docs/sveltekit.md — includes adapter-vercel switch, prerendering, $env tips. → Next.js/Nuxt/Other: docs/general.md covers framework-agnostic items.

Checklist (Ordered by Impact)

#	Optimization	Impact	CLI-checkable?	Plan Required
0	Use explicit adapter (e.g., adapter-vercel not adapter-auto)	Faster, no detection overhead	✅ Check config	Any
1	Turbo Build Machines	50-70% faster builds	❌ Dashboard only	Pro+
2	On-Demand Concurrent Builds	Eliminates deploy queue	❌ Dashboard only	Pro+
3	Prerender Static Pages	Fewer functions, faster TTFB	✅ Audit code	Any
4	Ignored Build Step	Skip irrelevant builds	✅ Check vercel.json	Any
5	Prioritize Production Builds	Prod deploys go first	❌ Dashboard only	Pro+
6	Eliminate Barrel Files	10-30% build speedup	✅ Audit code	Any
7	Audit & Trim Dependencies	Faster install + bundle	✅ Run depcheck	Any
8	GitHub Actions + --prebuilt	Full cache control, skip Vercel build	✅ Add workflow	Any
9	ISR for Dynamic Pages	Fewer cold starts	✅ Audit routes	Any
10	Instant Rollback	Zero-downtime recovery	✅ vercel rollback	Hobby: last only; Pro+: any

Pro plan items (#1, #2, #5): If not on Pro, check team plan first. These are the highest-impact free wins on Pro.

Dashboard Links (Can't Check via CLI)

For a team called <team-slug>:

• Turbo machines: https://vercel.com/<team-slug>/<project>/settings → General → Build Machine
• Concurrent builds: https://vercel.com/teams/<team-slug>/settings → Build Queue
• Prioritize prod: https://vercel.com/<team-slug>/<project>/settings → Git → Production prioritization

Docs

• docs/checklist.md — Full detailed checklist with how-to for each item
• docs/sveltekit.md — SvelteKit-specific optimizations
• docs/general.md — Framework-agnostic Vercel optimizations
• docs/github-actions-prebuilt.md — GitHub Actions + vercel deploy --prebuilt guide

Lessons Learned

Real-world findings from running all 10 checks on a SvelteKit project with 16-18s builds:

1. Half the checklist was overkill — builds were already fast. Triage step now prevents wasted effort.
2. ISR is irrelevant for auth-gated apps — every page served per-user content. Added decision tree.
3. adapter-auto → adapter-vercel was a missed win — not in original 10 but came up in dep audit. Now item #0.
4. Dashboard-only settings are the highest-impact items (Turbo, concurrent, priority) but can't be verified via CLI. Added direct links.
5. GitHub Actions + prebuilt only worth it at 60s+ — for fast builds, the Vercel Git integration is simpler and equally fast.
6. The dep audit found the project was already lean (11 deps, 84MB node_modules, 472K client bundle). Only one unused dep (clsx).
7. Team/plan tier gates most high-impact items — checking plan should be step 1.

Quick Start

1. Triage: Measure build times + check plan tier
2. Run applicable items from the checklist based on decision tree
3. If SvelteKit, also review docs/sveltekit.md
4. Track findings in a report file (e.g., vercel-speed-report.md)
5. For complex CI needs, follow docs/github-actions-prebuilt.md