Mavericks (or the drivers it ships with) is locking the window server for 50-100ms every time we touch the color table (10.8 was awesome and didn't do this). We've reduced our frame rate to compensate (it's better in this version), but it is noticeable when we do fast animations.

Is this also why when I hover over the menubar icon I get a beachball until it's done animating? I didn't see in this in the old version, but with today's I couldn't access the menu bar at all until it was finished fading.

I've been tracking this but haven't found a fix yet. There is sometimes a beachball if you interact with the menu item immediately after launch. I'll keep looking.

FWIW, Mac dev. here too, seeing the same issue in 10.9 with my app (beachball when interacting immediately after launch.) Haven't been able to track this down yet.

Thanks, good to know it's not just me. The stack trace says "Carbon" a lot, hmm.

I've had the exact same issue. I just updated to the new beta and my mouse cursor is still jumping. It only happens during the transitioning phase (for me at least), so it's only 20 seconds that my mouse is barely usable. The new features are worth the minor annoyance in my opinion.