Performance issues in Angular SSR configuration

Hello,

I think that this is a great project, Angular Universal has lacked public performance benchmark data since it's so different to other frameworks and Universal has been difficult to set up until quite recently. I think there are a few issues affecting the performance of the Angular Universal example which is currently the slowest SSR example.

Things like:

- Dynamically running the critical CSS inliner at runtime (an unsafe default): https://github.com/angular/universal/issues/2106
- Extra change detection cycles by not explicitly using onPush change detection: https://angular.io/api/core/ChangeDetectionStrategy
- Missing a track by function to keep track of individual rows and not re-rendering the whole table: https://angular.io/api/core/TrackByFunction
- Calling methods from inside templates which are invoked on each change detection cycle: https://blog.devgenius.io/avoid-calling-expressions-in-template-of-angular-39439c547653

If we make some PRs for that is there a contribution process or should we just make a bunch of PRs?

Thanks!