Thanks for the detailed report, and sorry about that. You were right on both counts.

Version 4.2.1 (released today) only renders the cards near the viewport, so large collections no longer lock up the tab. Picking a root folder to display is the next thing I'm working on.

If you get a chance to try it again, I'd really appreciate hearing whether it holds up with your 10k+ collection. Either way, thanks for taking the time to write this up.