Initial incremental compilation is slower than expected on large projects #32128
Description
Command
serve
Is this a regression?
- Yes, this behavior used to work in the previous version
The previous version in which this bug was not present was
No response
Description
When serving a large project, after the first time saving file changes, the rebuild takes about as long as an initial build. On the subsequent times saving file changes, the rebuild time is much lower.
Initial build -> 46 seconds
Incremental build -> 40 seconds
Incremental build -> 5 seconds
Minimal Reproduction
Repo with new Angular v21 project that contains 50 routes and 10K components.
https://github.com/brandonroberts/angular-large-project
- Clone repo, run npm install
- Run
npm start - Note initial build time
- Save a change to one of the pages
- Note build time
- Save another change
- Note the build time
Exception or Error
Your Environment
Angular CLI : 21.0.3
Angular : 21.0.5
Node.js : 22.14.0
Package Manager : npm 10.9.2
Operating System : darwin arm64
┌───────────────────────────┬───────────────────┬───────────────────┐
│ Package │ Installed Version │ Requested Version │
├───────────────────────────┼───────────────────┼───────────────────┤
│ @angular/build │ 21.0.3 │ ^21.0.3 │
│ @angular/cli │ 21.0.3 │ ^21.0.3 │
│ @angular/common │ 21.0.5 │ ^21.0.0 │
│ @angular/compiler │ 21.0.5 │ ^21.0.0 │
│ @angular/compiler-cli │ 21.0.5 │ ^21.0.0 │
│ @angular/core │ 21.0.5 │ ^21.0.0 │
│ @angular/forms │ 21.0.5 │ ^21.0.0 │
│ @angular/platform-browser │ 21.0.5 │ ^21.0.0 │
│ @angular/router │ 21.0.5 │ ^21.0.0 │
│ rxjs │ 7.8.2 │ ~7.8.0 │
│ typescript │ 5.9.3 │ ~5.9.2 │
│ vitest │ 4.0.15 │ ^4.0.8 │
Anything else relevant?
No response