Select a periodic element in the demo, so an overlay gets painted on it, fine. Then, rotate the model. The page becomes quite busy, pegging a core. According to the profiler, it seems that we try to send a ton of overlay highlights during rotation, and it takes about 20 seconds to catch up. During that time, nothing gets highlighted. We should do something smarter here. For starters, we could drop highlight messages on the floor if the queue gets past the point where the page overlay could keep up. I am not quite sure where these messages are being queued up at the moment, I would have to think about it harder.
<rdar://problem/28228568>