Cutting frontend build times by 75%

At Kinetic Solutions Group I work on Vivi, a product for building and deploying digital employees (agents). The UI wasn’t slow in the browser so much as slow to ship—cold builds and HMR friction were eating iteration time.

We cut frontend build times by roughly 75% by migrating to rolldown-vite and Tailwind v4. Here’s what mattered.

Measure before you migrate

We started with wall-clock numbers everyone trusted: cold production build, cold dev server ready time, and a representative HMR edit. Without that baseline, “feels faster” is useless in a PR review.

Vite (again), but with a faster bundler core

I’d already led a Webpack → Vite migration at Blameless years earlier. The lesson carried over: tooling migrations pay off when the whole team feels them daily. Rolldown-vite was the next step—same Vite workflows, less waiting.

Practical tips:

• Keep the migration scoped: config, plugins, and CI first—don’t “clean up” unrelated debt in the same PR
• Treat CSS tooling as part of the build path, not an afterthought
• Fail the PR if CI build time regresses beyond an agreed budget

Tailwind v4 as a build-time win

Tailwind v4 wasn’t only a design-token refresh for us—it simplified how styles entered the pipeline. Fewer moving parts in PostCSS-land meant fewer surprises in CI.

What I’d do again

1. Publish the before/after numbers in the PR description
2. Migrate on a quiet week with a rollback plan
3. Pair the bundler change with CSS pipeline cleanup so you don’t leave half the old stack behind

Fast builds aren’t vanity metrics. They’re how a frontend team stays willing to refactor.