Slowdown in esbuild build time in 20.3.1 and newer

[v-jaros]

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

20.3.0

Description

ng serve suddenly takes almost twice as long to build, no change in config or code, just dependencies update - see package.json examples

package.json that takes 35s to build
"dependencies": {
"@angular/animations": "20.3.0",
"@angular/cdk": "20.2.2",
"@angular/common": "20.3.0",
"@angular/compiler": "20.3.0",
"@angular/core": "20.3.0",
"@angular/forms": "20.3.0",
"@angular/platform-browser": "20.3.0",
"@angular/platform-browser-dynamic": "20.3.0",
"@angular/platform-server": "20.3.0",
"@angular/router": "20.3.0",
...
},
"devDependencies": {
"@angular/build": "20.3.0",
"@angular/cli": "20.3.0",
"@angular/compiler-cli": "20.3.0",
"@angular/language-service": "20.3.0",
...
}

package.json that takes 60s to build
"dependencies": {
"@angular/animations": "20.3.1",
"@angular/cdk": "20.2.2",
"@angular/common": "20.3.1",
"@angular/compiler": "20.3.1",
"@angular/core": "20.3.1",
"@angular/forms": "20.3.1",
"@angular/platform-browser": "20.3.1",
"@angular/platform-browser-dynamic": "20.3.1",
"@angular/platform-server": "20.3.1",
"@angular/router": "20.3.1",
...
},
"devDependencies": {
"@angular/build": "20.3.1",
"@angular/cli": "20.3.1",
"@angular/compiler-cli": "20.3.1",
"@angular/language-service": "20.3.1",
...
}

Minimal Reproduction

ng serve

Exception or Error

Your Environment

=== SLOW BUILDS ENV ===
Angular CLI: 20.3.1
Node: 22.15.1
Package Manager: npm 10.9.2
OS: win32 x64


Angular: 20.3.1
... animations, build, cli, common, compiler, compiler-cli, core
... forms, language-service, platform-browser
... platform-browser-dynamic, platform-server, router

Package                      Version
------------------------------------
@angular-devkit/architect    0.2003.1
@angular-devkit/core         20.3.5
@angular-devkit/schematics   20.3.5
@angular/cdk                 20.2.2
@schematics/angular          20.3.1
rxjs                         7.8.2
typescript                   5.8.3
zone.js                      0.15.1

=== FAST BUILDS ENV ===
Angular CLI: 20.3.0
Node: 22.15.1
Package Manager: npm 10.9.2
OS: win32 x64


Angular: 20.3.0
... animations, build, cli, common, compiler, compiler-cli, core
... forms, language-service, platform-browser
... platform-browser-dynamic, platform-server, router

Package                      Version
------------------------------------
@angular-devkit/architect    0.2003.0
@angular-devkit/core         20.3.5
@angular-devkit/schematics   20.3.5
@angular/cdk                 20.2.2
@schematics/angular          20.3.0
rxjs                         7.8.2
typescript                   5.8.3
zone.js                      0.15.1

Anything else relevant?

No response

[clydin]

Can you selectively downgrade specific packages to attempt to assist in determining the root cause?
The most relevant packages would be @angular/build, @angular/compiler, and @angular/compiler-cli.

The @angular/build package only had 2 commits from 20.3.0 to 20.3.1. One of which was a logging change and the other an update of vite. (Details: angular/angular-cli@20.3.0...20.3.1)

[v-jaros]

It seems to be caused by @angular/compiler-cli - having all packages in version 20.3.1 - changed just compiler-cli to 20.3.0 and build is fast as before.

[JoostK]

I expect this to be due to #63754, which is almost a straight revert of the change made in #57291 which reintroduces the performance footgun. The proper fix would be #57337

[JeanMeche]

To confirm Joost's suspicion, you can disable the diagnostic in tsconfig.json with:

{
  "angularCompilerOptions": {
    "extendedDiagnostics": {
      "checks": {
        "interpolatedSignalNotInvoked": "suppress"
      }
    }
  }
}

[v-jaros]

I've tested it and can confirm that "interpolatedSignalNotInvoked": "suppress" restores the original build speed.