Looks like some kind of focus manager spin happens when trying to run the Gengrid Update Speed test
Sooo - I manaed to bring down the times. However, its still lagging, the scrolling experience its less than perfect. However, on every group_calculate we walk a list of 5K items just by the design of gengrid, and that is slowing things down *a lot*. Not sure what else we can do here ....
Just tested it. Previously, pressing "Page Down" was so slow Gnome offered to kill the app because it was unresponsive. Now it takes 3 seconds to update.
So performance is still an issue, but at least it does not look like a "lockup".