"Compiling" is vague here; for TS I think you need to distinguish bundling from type-checking.

If you're talking about bundling the entire app, 120 seconds down to 10 seconds is a great saving, but other bundlers can do it much faster already. Most people don't bother using TSC to bundle their code. I can understand why Microsoft might insist on using it, but it's not typical.

For type-checking the entire app, I would see that as akin to running all the unit tests. 120 -> 10 seconds is excellent, but not something that should be a constant bottleneck in your development workflow.

I can definitely see that 10x improvement being crucial on large teams (and/or LLM swarms) where the speed of the CI queue becomes a bottleneck.