Full build with Rollup on all of my bundles for my project took around 10 minutes. IDK what my KLoC count is, but it's probably in the 25 to 50K range, with very few dependencies. I had a lot of complexity in my build scripts to try to subdivide related bundles into individual build commands to get the day-to-day rebuilds down to the 1 to 2 minute range. I had to run TypeScript in watch mode separately to emit individual JS files from my TS code for each module, and then only let Rollup bundle the JS code (the available TS plugins were just too slow), so I had tons of garbage files all over everywhere and occasionally they would get out of synch. It was a mess and it was extremely difficult to explain everything to newcomers.
With ESBuild, everything, all the things, build in 0.25 seconds. Build script has massively reduced complexity, as there's no point in running any command other than "build all". There's just the TS code and the output. I'm still running TypeScript in watch mode separately to get compilation errors on the fly (ESBuild doesn't run the TS compiler itself, it has a custom-built translator that optimistically throws away type information), but I no longer configure it to emit translated code. And did I mention the build script is massively simpler?
With ESBuild, everything, all the things, build in 0.25 seconds. Build script has massively reduced complexity, as there's no point in running any command other than "build all". There's just the TS code and the output. I'm still running TypeScript in watch mode separately to get compilation errors on the fly (ESBuild doesn't run the TS compiler itself, it has a custom-built translator that optimistically throws away type information), but I no longer configure it to emit translated code. And did I mention the build script is massively simpler?