vercel-performance-tuning

name	vercel-performance-tuning
description	Optimize Vercel deployment performance with caching, bundle optimization, and cold start reduction. Use when experiencing slow page loads, optimizing Core Web Vitals, or reducing serverless function cold start times. Trigger with phrases like "vercel performance", "optimize vercel", "vercel latency", "vercel caching", "vercel slow", "vercel cold start".
allowed-tools	Read, Write, Edit, Bash(vercel:*), Bash(npx:*)
version	1.18.0
license	MIT
author	Jeremy Longshore <[e-mail]>
tags	["saas","vercel","performance","caching","optimization"]
compatibility	Designed for Claude Code

Vercel Performance Tuning

Overview

Optimize Vercel deployment performance across four levers: edge caching, bundle size reduction, serverless function cold start elimination, and Core Web Vitals improvement. Uses real Vercel cache headers, ISR, and Edge Functions for maximum performance.

Prerequisites

• Vercel project deployed with accessible URL
• Access to Vercel Analytics (dashboard)
• Bundle analyzer available (@next/bundle-analyzer or similar)

Instructions

Step 1: Establish Performance Baseline

# Check deployment size and function count
vercel inspect https://my-app.vercel.app

# Run Lighthouse via CLI
npx lighthouse https://my-app.vercel.app --output=json --quiet \
  | jq '{performance: .categories.performance.score, lcp: .audits["largest-contentful-paint"].numericValue, cls: .audits["cumulative-layout-shift"].numericValue}'

# Check bundle size (Next.js)
ANALYZE=true npx next build
# Opens bundle analyzer report in browser

Enable Vercel Analytics in the dashboard under Analytics tab for ongoing monitoring.

Step 2: Configure Edge Caching

// api/cached-data.ts — cache API responses at the edge
import type { VercelRequest, VercelResponse } from '@vercel/node';

export default function handler(req: VercelRequest, res: VercelResponse) {
  // Cache at Vercel edge for 60s, serve stale for 300s while revalidating
  res.setHeader('Cache-Control', 's-maxage=60, stale-while-revalidate=300');
  res.json({ data: (), :  ().() });
}