--incremental builds are a bit slower after the 20250805 release

[joshcartme]

Parts of the incremental build (like changes compute time) are now significantly faster, but overall incremental builds are a bit slower.

memprofiles for the warm builds shown below:

• 20250804
• 20250805

Diagnostic output:

2025-08-04 cold:

Files:                    48433
Lines:                  6937671
Identifiers:            8358012
Symbols:               19135744
Types:                  9232629
Instantiations:        33855859
Memory used:          15656224K
Memory allocs:        274036051
Config time:             1.981s
BuildInfo read time:     0.384s
Parse time:              2.853s
Bind time:               0.001s
Check time:             25.959s
Emit time:               3.792s
Changes compute time:    6.985s
Total time:             41.958s

2025-08-04 warm:

Files:                   48433
Lines:                 6937671
Identifiers:           8358012
Symbols:               4472788
Types:                     348
Instantiations:              0
Memory used:          6647971K
Memory allocs:        36869491
Config time:            1.989s
BuildInfo read time:    4.331s
Parse time:             2.999s
Bind time:              0.001s
Check time:             0.007s
Emit time:              0.006s
Changes compute time:   8.441s
Total time:            17.776s

2025-08-05 cold:

Files:                    48433
Lines:                  6937671
Identifiers:            8358012
Symbols:               19135734
Types:                  9232433
Instantiations:        33855859
Memory used:          17073228K
Memory allocs:        349832901
Config time:             2.014s
BuildInfo read time:     0.393s
Parse time:              2.970s
Bind time:               0.001s
Check time:             27.795s
Emit time:               4.138s
Changes compute time:    2.127s
Total time:             39.440s

2025-08-05 warm (substantially more memory allocs):

Files:                    48433
Lines:                  6937671
Identifiers:            8358012
Symbols:                4472788
Types:                      348
Instantiations:               0
Memory used:           8064926K
Memory allocs:        223219055
Config time:             2.028s
BuildInfo read time:     9.537s
Parse time:              4.549s
Bind time:               0.001s
Check time:              0.045s
Emit time:               2.976s
Changes compute time:    3.566s
Total time:             22.705s

[jakebailey]

The profile seems to show it all:

That and this, but I think that's preexisting:

[joshcartme]

It's not nearly as pronounced as in our private codebase, but I think I have a repro with https://github.com/elastic/kibana, which has tens of thousands of typescript files.

My steps are:

• clone kibana
• Modify the root tsconfig.json by adding the following to "include": "**/*.js", "**/*.ts", "./typings/**/*"
  • I cobbled this together by looking through some of the other tsconfigs in the repo, I'm not at all trying to make something that's "correct", just something that typechecks a whole lot of files
• npx @typescript/native-preview --project tsconfig.json --noEmit --diagnostics --incremental
• run that again and observe that memory allocs and total time are increased on the second run

Doing that I'm seeing a first run with ~97 million allocs and ~12.6 seconds total time and a second run with ~102 million allocs and ~13 seconds total time. The .tsbuildinfo file is ~20 megabytes

Again this is not nearly as pronounced as I see in our private repo, but the difference is consistently there on the second run.