Case Study: We Cut Bundle Size by 45% Using Svelte 5.0 and Vite 6.0

When our e-commerce dashboard’s initial bundle size hit 1.2MB gzipped, we knew we had a problem: 38% of users on 3G networks abandoned the app before the first paint. After migrating to Svelte 5.0 and Vite 6.0, we slashed that bundle to 660KB gzipped—a 45% reduction—with zero regressions in functionality, and a 220ms improvement in first contentful paint (FCP) across all network conditions. For context: our team maintains a B2B e-commerce dashboard used by 12,000+ merchants globally. The app inc