Performance issues when expanding comments with many child comments

[boscojwho]

Describe the bug When expanding comment with many child comments, main thread appears to be blocked.

Expected Behavior Should bounce that work off on background thread, and have a progress indicator show while that's happening.

Actual Behavior Comment expansion is blocking main thread.

To Reproduce

1. Open post with comment with hundreds of replies.
2. Collapse/expand that comment.

Mlem Information:

• Latest commit on /dev branch.

[boscojwho]

I can take a look at this after #841 is merged in =)

[EricBAndrews]

Looks like the issue is the animation itself--I can't find any Mlem code that's running particularly slowly. We probably shouldn't be animating the whole thing, though--something to look into for 2.0

[Sjmarf]

Fixed in 2.0