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 |
| **...