Massive freezes when opening popup windows

This has been happening for some time now, but it's gotten worse over time. Basically, under some circumstances that I'm yet to uncover, Mutter freezes when opening popup windows. Not the window, but the entire compositor.

One way to try and reproduce it is with GNOME Web 3.32:

1. Open Web
2. Try and type something in the url entry
3. Observe the massive freezes

Each key press freezes the compositor for about ~2 seconds. When I'm caught off guard and start typing like crazy, that can easily become an entire minute frozen.