vercel-speed-audit

# 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**: ```bash # 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](docs/checklist.md)** — Full detailed checklist with how-to for each item - **[docs/sveltekit.md](docs/sveltekit.md)** — SvelteKit-specific optimizations - **[docs/general.md](docs/general.md)** — Framework-agnostic Vercel optimizations - **[docs/github-actions-prebuilt.md](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`