NoopAnimationDriver isn't as Noop as its name suggests

🚀 Feature request

Reduce performance hit on ssr when using angular animations.

• angular 9.1.3

Description

Profiling our ssr:

There is this AnimationEngine.flush() call at the end, that as far as I can tell, adds ~500 ng-star-inserted classes to all elements with an *ngIf. And also sprinked some cpu cycles in between all over the app.

I found no official way to disable this behavior.

I monkeypatched these three methods away:

const animations = require('@angular/animations/browser');
Object.assign(animations.ɵAnimationEngine.prototype, {onInsert: () => {}, register: () => {}, registerTrigger: () => {}});

Made the ssr ~5% faster, reduced memory consumption & reduced the html output by 8kb (by omitting all those ng-star-inserted classes). The html stil works as without the patch.

[pauldraper]

NoopAnimationDriver isn’t no-op from a functional rendering perspective either: https://github.com/angular/angular/issues/27917 (ngAfterViewChecked is fired with different DOM states if NoopAnimationDriver is present.)

[angular-automatic-lock-bot[bot]]

This issue has been automatically locked due to inactivity. Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}