TanStack Start: autoCodeSplitting option not available, causes tons of HTTP requests in dev

[mikecfisher]

Hey, I'm running into a dev performance issue with TanStack Start that I wanted to raise.

Start's config schema explicitly omits the autoCodeSplitting option that's available in standalone Router. This means routeTree.gen.ts statically imports every route upfront.

For my app with ~100 routes, this translates to 700+ HTTP requests on every page load in Vite dev mode. It's bad enough that it hits ngrok's rate limit (360 req/min) and makes the dev server painfully slow.

I know Router v2 plans to enable autoCodeSplitting by default (#975), but in the meantime is there a reason Start omits this option? Or is there another way to get lazy route tree imports working with Start?

The manual .lazy.tsx approach helps but doesn't fully solve it since routes with beforeLoad guards still need their config file loaded statically.

Happy to provide more details or a reproduction if helpful.

[schiller-manuel]

Start has autoCodeSplitting enabled by default. autoCodeSplitting still leads to importing each route file in the routeTree.gen.ts file since the route definition itself is needed. a reproducer would be interesting to look at to see if there is anything we could do or if this is only truly solvable by vite's upcoming bundled dev mode.