This IS wave 24. I had a pretty insane run, with a lot of sawmills and sawmill upgrades
As is visible in the screeshot (two Ranger Camps on the top left), some of the buildings wouldn't unselect after being placed. Placing buildings in general was pretty floaty and sometimes took a few tries.
You couldn't move already placed buildings anymore (as in, they were impossible to even pick up) and the card selection starts to be hard to click with a lot of cards. I think that's it.
Honestly though, I was pretty amazed that the game still ran at all, I was putting quite a bit of a strain on it