I'm getting to like Mountain Lion, in general, apart from one thing - Mission Control. I've been hoping it would be improved by now. Both functionally and in terms of optimisation. Functionally it's so much less useful than 10.5 to me because of the way it lays things out. It's harder to read because of the stacked windows as well as the strange new algorithm for actually 'box-packing' which seems a lot less tidy, than 10.6 or 10.5/4/3. Lots of screen real estate, as well as GPU resources are wasted by GUI fluff. The Spaces could probably have used a lot smaller area / even just a tab-like bar at the top, just as an example... For me, it's been awful since 10.7, and hasn't got any better. And the worst thing of all is the frame-rate. Whereas my 2002 G4 Powerbook could happily run 20-30 windows of Exposé acceptably smoothly on 10.3.9, my top end 2013 machine will sometimes go as bad as 1fps (to the point where you don't even see the windows slide onto the screen, they sort of judder, pause, and just appear on it instead.) This can be with as few as, say 10-15 windows, with nothing heavy running, with iGPU or dGPU. Watching this work smoothly back this long ago makes me sad: http://www.youtube.com/watch?v=mAvHMDR1N3U (Exposé original demo) Looks loads more functional too... Could there actually be something wrong with my install? I somehow doubt it, as this is my 3rd RMBP due to image retention, and they've all exhibited it from day 1. As of late, I've actually dropped Mission Control from my workflow, pretty much entirely. Which is a massive step back as I used Exposé pretty much constantly before, tied to hot corners, doing 'power-moves' like dragging files into the corner of the screen to trigger it and move them around like that etc. I've since reverted to just clicking icons and using things like window re-positioning as I was doing in 10.2... talk about progress! I never had a problem with lag in Safari as others have said, in fact it runs buttery smooth since 10.8.3, so I now know the RMBP can throw around a lot of hires pixels very smoothly if need be... As a coder, the performance of Mission Control feels to me more like a bug / really badly optimised bit of code, but this is just my intuition (for example, it doesn't seem to make any difference to the frame-rate whether I'm on iGPU or dGPU, etc...) How about you guys, how do you find it? Is it any better on other Macs? Is this a Retina-specific performance thing? Is there any hope of a performance-fix?