Significant Slowdown in M3 Runtime Compilation

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

Building our NX monorepo, particularly when utilizing M3 material components at runtime, is experiencing noticeable delays. This slowdown in compilation time is impacting our development efficiency.

Without M3, the compilation process takes approximately 2 seconds. However, with M3 integrated, the compilation time extends to 40 seconds or more.

Reproduction

StackBlitz link:
Steps to reproduce:
1.
2.

Expected Behavior

.

Actual Behavior

.

Environment

• Angular: v18.0.0-rc.0
• CDK/Material: v18.0.0-rc.0
• Browser(s): chrome
• Operating System (e.g. Windows, macOS, Ubuntu): mac

[crisbeto]

I believe that Nx uses some sort of build caching. Do you see these slowdowns consistently or only on the initial build? Also what changes did you make to enable M3? We export all the APIs through the same _index.scss so I would expect the build graph to look identical no matter what version of Material you're using.

@crisbeto
slowdown is consistent

@use '@angular/material' as mat;
@use 'sass:map';

mat.$theme-legacy-inspection-api-compatibility: false;

// Create a theme with the specified color type and density.
@function create-theme($type: light, $density: 0, $primary: mat.$blue-palette, $tertiary: mat.$violet-palette) {
  @return mat.define-theme(
    (
      color: (
        theme-type: $type,
        primary: $primary,
        tertiary: $tertiary
      ),
      density: (
        scale: $density
      ),
      typography: (
        brand-family: 'Be Vietnam Pro',
        plain-family: 'sans-serif',
        // regular-weight: 400,
        // medium-weight: 500,
        // bold-weight: 700
      )
    )
  );
}

// Define the default (light) theme.
$light-theme: create-theme(
  $type: light
);

// Create our dark theme.
$dark-theme: create-theme(
  $type: dark
);

// Include the common styles for Angular Material. We include this here so that you only
// have to load a single css file for Angular Material in your app.
// Be sure that you only ever include this mixin once!
@include mat.core();

// Include the default theme styles.
html {
  @include mat.all-component-themes($light-theme);
}
@include mat.typography-hierarchy($light-theme);

.dark-theme {
  // Include the dark theme color styles.
  @include mat.all-component-colors($dark-theme);
}

// Create classes for all density scales which are supported by all MDC-based components.
// The classes are applied conditionally based on the selected density in the dev-app layout
// component.
$density-scales: (0, -1, -2, -3, -4);
@each $scale in $density-scales {
  .density-#{$scale} {
    $density-theme: create-theme(
      $density: $scale
    );
    @include mat.all-component-densities($density-theme);
  }
}

.default {
  $light-theme: create-theme(
    $type: light,
    $primary: mat.$azure-palette,
    $tertiary: mat.$blue-palette
  );

  // Create our dark theme.
  $dark-theme: create-theme(
    $type: dark,
    $primary: mat.$azure-palette,
    $tertiary: mat.$blue-palette
  );

  // Theme Config
  @include mat.all-component-colors($light-theme);

  &.dark-theme {
    @include mat.all-component-colors($dark-theme);
  }

  // Enable backwards-compatibility CSS for color="..." API & typography hierarchy.
  &.back-compat {
    @include mat.color-variants-backwards-compatibility($light-theme);
    @include mat.typography-hierarchy($light-theme, $back-compat: true);

    &.dark-theme {
      @include mat.color-variants-backwards-compatibility($dark-theme);
    }
  }
}

Nx 18, 19
Angular 18 rc 0 even with experimental 17 package

before m3 and after m3 build times and runtimes doubled up

[crisbeto]

Can you also post what your theme looked like for M2?

[crisbeto]

I've sent out #29009 which seems to cut the compilation time at least in half for M3.