Interesting performance bottleneck with large list

[Bouke]

An API endpoint unexpectedly returned a very large set of items (~45k). The load happens through Ember Data and the processing went fine. However the page became unresponsive and investigation showed an unexpected bottleneck: getBoundingClientRect. See also this trace in Safari:

While I agree that listing 45k items isn't a practical use-case, I do think that it shouldn't cause the page to become unresponsive. This call is originating from setupMutationObserver. Maybe a debounce of some sorts would help?

This is on EPS 4.1.2, EBD 3.0.13 and Ember 3.25.1.

[derrabauke]

We implemented / copied an approach utilizing VerticalCollection of the "@html-next/vertical-collection" package. Works quite well with large lists. Hope this inspires ;)

[betocantu93]

We also did that in ember-eui/combo-box