--incremental takes a lot of time not accounted for by --diagnostic

[joshcartme]

Incremental is great and I'm loving what it does for --watch. In our codebase there is around 15 seconds that is not accounted for by --diagnostic.

Non incremental:

$ yarn run tsgo --project tsconfig.tsgo.json --diagnostics
Files: 48262
Lines: 6893512
Identifiers: 8304232
Symbols: 18835276
Types: 9079974
Instantiations: 33093464
Memory used: 14199174K
Memory allocs: 233412728
Config time: 1.949s
Parse time: 2.939s
Bind time: 0.240s
Check time: 25.367s
Emit time: 0.027s
Total time: 30.533s

Incremental

$ yarn run tsgo --project tsconfig.tsgo.json --incremental --diagnostics
Files: 48262
Lines: 6893512
Identifiers: 8304232
Symbols: 4444747
Types: 348
Instantiations: 0
Memory used: 6722281K
Memory allocs: 37396964
Config time: 1.952s
Parse time: 2.994s
Bind time: 0.001s
Check time: 0.006s
Emit time: 0.004s
Total time: 20.228s

memprofile.pb.gz
cpuprofile.pb.gz

All of this was generated using the 20250725.1 release, on MacOS. Maybe of note, the .tsbuildinfo file is 82M right now.