CSS sourcemaps, being a basic assets in frontend tooling for many years, are still unsupported in Vite(<a href="https://github.com/vitejs/vite/issues/2830" rel="nofollow">https://github.com/vitejs/vite/issues/2830</a>). Being an open issue for that long, while sourcemaps are supplied for free with tools like ESBuild & SCSS, are perhaps an indication of too much complexity in Vite? About build performance; ESBuild(and SWC as well) happily build large projects within reasonable time(<200ms). I doubt that skipping bundling all-together, by using ES-Modules during development, is worth the extra hassle in tooling. It made sense during the Webpack/Vuepack/Parcel 1 era, but not that much anymore since ESBuild happened. Spending some extra time in writing a custom buildscript (ESBuild + SCSS + simple async task manager + Chokidar + Tinylr or something similar) pays itself back really quick when a project gets larger.