Retrospective: Adopting Next.js 15 and Vercel 2026.03 Reduced Our Deployment Time by 70% in 3 Months At our mid-sized SaaS company, deployment speed was a constant pain point. Before Q4 2025, our average production deployment took 12 minutes flat: 4 minutes for build, 6 minutes for test suites, 2 minutes for Vercel rollout. For a team pushing 15+ deploys a day, that added up to 3+ hours of cumulative wait time daily, slowing feature velocity and frustrating developers. Background: The Pre-Migration Pain We were running Next.js 13.5 with Vercel's 2024.12 runtime. Our build pipeline relied on Webpack with custom plugins, and our test suite ran sequentially in CI. We had frequent build cache misses, and Vercel's older runtime lacked support for incremental static regeneration (ISR) optimizations we needed for our content-heavy dashboard. Every deployment felt like a gamble: 1 in 10 failed due to cache inconsistencies, requiring full pipeline reruns.…