iMac 5K Retina extremely slow Mission Control

Yep, really. Apple could fix the (apparent) M290X driver issues any day, but I didn't really want to wait. And $250 over the life of the machine seemed ok, considering it will raise the resale value of it some as well. And now I have a faster graphics card, not sorry about that.

So, I seem to have solved the problem completely, albeit in a far-from-ideal way.

It seems that heading to System Preferences > Accessibility and toggling 'Increase Contrast' on makes everything "buttery smooth", with no noticeable slowdowns or lags whatsoever.

It does make everything looks really ugly, but it seems to fix all problems with laggy animations.

I also own the iMac 5K base model and am experiencing the same problems. I made some benchmarks and decided to post them here for people who read this thread and now are scared that Graphics / the UI is much slower than on normal non-Retina Macs, also, my results seem confirm that it's a software issue. The problems with most benchmarks on the web is, that they don't take in account that the iMac 5K has to push 4 times more pixels than the normal 27" iMac. For example I ran Cinebench (which runs at non-retina resolution on the 5K) and the score was about 4 times higher than on my previous non-retina Mid 2011 21.5" iMac with the AMD Radeon HD 6750M 512MB where I never had any graphic issues while working (I use mostly Emacs, Xcode and a lot of Safari). I decided to use the outdated Xbench for benchmarking because it runs everything in retina resolution when possible and, as far as I can see, runs tests that show much better how the interface may perform.

The benchmark with Xbench showed that compared to the iMac 21.5" Mid 2011 with the AMD Radeon HD 6750M 512MB ...

- Quartz Graphics were about 30% slower

- OpenGL Graphics were a little bit faster

- the "User Interface Test" results were a little bit better

... on the iMac 5K base model. View full results.

This probably means that the iMac 5K can push 4 times more pixels nearly as fast as my previous iMac could push pixels on its non-retina screen. This also complies with the Cinebench results being 4 times faster on the 5K. I'm no benchmarking expert so you may take these results with a grain of salt, also Xbench was updated the last time in 2006 so it may not be using the benefits of Apples latest graphic framework.

PS: Would be great if someone who has Mac with a slower graphics card that really struggles with Mission Control (not sure if that really exists thought) could post his Xbench scores so we see how far the iMac 5K is away from that.

I can not completely confirm that but the "Increase Contrast" option fixes it completely but it seams to be better. Also, I've now been running iStat menus for some time and the GPU memory is almost empty all the time, so this can not be the problem.

Same Trouble here with base 2gb graphic card.

Momentary fixed with increase contrast options, but i prefer to take 4gb graphic card (which has got a better graphic chip) and return this to apple.

Any folk installed latest OS X Yosemite 10.10.2 beta to see if this issue was solved?

Thanks.

My iMac 5K do also some crazy things:

In Finder, wehen i press SpaceBar to preview a picture, it comes up after 1-3 seconds :-(

I think it will be the same problem as written form the others.

Greetings from Germany

imac 5K 4ghz, 32gb ram, small graphic card.

Sadly, 10.10.2 does not fix the issue so far.

5k 27" 4Ghz i7, M290X, 32GB ram, two screens here. Same problem, slow mission control, window dragging, previews, everything UI lags tremendously, sometimes takes 1-2 seconds just to react. Unbelievable lack of QA from Apple, and not a word of problem acknowledgment to their customers either. Sad.

The only way around this annoying problem seems to be changing the iMac screen resolution to 2560x1440 non HiDPI/Retina using something like switchResX, as some users suggested.

10.10.2 still in beta, hope to see official release to fix it.

You might want to look at which apps you have installed. When I uninstalled XtraFinder everything got much much better. I was ready about to return this thing due to the 1-2 second UI lag for just about anything, including moving windows around.. For some reason on retina displays the Finder tab apps are really messing with the UI. I had the same issue with my retina macbook pro as well.

Many people here claim it is a software issue, but I don't buy that. If it is a software issue, why is it smooth with just one application open, and gets more and more slow when more applications are opened? All the workarounds presented here possibly just amount to the fact that the graphics card has to calculate less, so it becomes smooth again.

In any case, even it is is a software issue, my guess is that Apple will never fix it, similar to many issues Apple has never cared about in the past. Just return the machine and take the one with the better graphics card, or wait for the second generation iMac retina, which is what I do.

i agree! i called apple several times and went to the apple store. i insisted to get my 5k imac exchanged to the same model with the better video card, so thats what they do. also check out how the imac reacts when you boot it in save mode - its almost not working graphics are so poor!

Same problem here too. I figured it was an issue with the OS because it works fine when the computer starts up. I have 32GB of RAM and an SSD, so it's not that. If it is the video card, why would Apple sell a configuration that couldn't run their OS smoothly on one of their most high end computers? I was hoping an OS fix would come along to resolve this but none so far. For those of you who exchanged your iMac for one with the better graphics card, were you able to do this after the 14 days?

Didn't try to return it after the 14 days. I got it authorized before the 14 days and after that you have another 14 days or so to actually return it.

No matter, I'm sure if you make a stink (no need to be rude though), and mention that this is a known problem and you will be buying the higher end model they would allow it.