Description

Safari is slow to update the persistent list view when actions like selection, additions or removals occur.

Step-by-step reproduction instructions

1. Navigate to the post editor wp-admin/post-new.php

2. Open list view:
   

3. Try adding new blocks (Are they slowly added?)

4. Try selecting blocks by clicking on a list view item.
   Expected: list item turns blue
   Actual: It takes quite a while for the list item to turn blue (selected). Notice how the focus happens pretty much instantly.

Screenshots, screen recording, code snippet

Environment info

Gutenberg trunk (cb36e1c) / Safari 14.1.2

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes