iMac 5K Retina extremely slow Mission Control

Same thing here ! I updated yesterday hoping it will fix the problem...

i bought the Retina 4GHz i7 / 32 g / 4g Radeon... for the price i paid... the UI in Mission Controls feels so slow... god ! AND its worst then before the upgrade

- PA -

Worked for me. Its super fast now. Thanks for your post!

Greets

OK, one more update for today:

I've found that if you select Accessibility > Reduce Transparency, it's actually pretty decent when activating Mission Control. However - as soon as you uncheck that option, it gets really sluggish - more so than it did in 10.10.1. And even worse, it will only return to normal with a full reboot.

Thus, for the time being, I'm going to turn on Reduce Transparency and leave it along until at least 10.10.3 comes out.

Thanks,

- Scott -

The reduce Transparency doesn't seem to help. After this update very basic things have become slow too, such as switching between programs and windows. I'm really shocked at how slow one of their top of the line computers is running and that they still don't have a fix. I love Apple, but their software gets more and more buggy with every release. I really hope they fix this soon!

iMac 5K , i7, 8Go, M295X, Yosemite 10.10.2

Same problem, Mission control is very slow with 7 or more apps opened.

Very annoying for a 3200€ mac !

10.10.3 first beta seems to bring no improvement. Everything is smooth after a reboot, but after working for a few hours or letting the iMac sleep overnight the problem is the same. Even switching from one app to another is delayed. Moving a window around lags and sometimes even clicking a menu item has a delay.

nope, it does not help.

this helps: enable Increase Contrast (Reduce Transparency will also be enabled automatically). the Mission Control lag will be dramatically improved.

I have the base model 5K too and after experimenting with various different things, and trying out another machine in the Apple store, I've come to the conclusion that the problem gets worse the more apps/icons you have running in the menu bar. I normally have Dropbox, Google Drive, OneDrive, Fantastical and Flickr Uploader loaded in the menu bar, and with 1/2 a dozen apps running on screen the Mission Control is super jerky and horrible, however, when I close all the apps running in the menu bar it gets a lot smoother. Don't get me wrong, it's still not perfect (even my basic MacBook Air is better), but it's nowhere near as bad. Any thoughts on this one?

OK - I think I finally have a solution! Download and install TotalSpaces: http://totalspaces.binaryage.com

TotalSpaces takes over Mission Control, so to speak, and in my testing, does not suffer from any of the lag. Right now, I have the following applications open: Safari, Mail, Messages, BusyCal, Things, Chrome, VMWare, SQL Developer (Java-based app which would destroy Mission Control) and Spotify, and there is ZERO lag!

TotalSpaces also gives you a number of other features not found in Mission Control, such as stacking rows and columns of desktops, more transitions and synchronization of changes for multiple monitors. You can activate it via a hot key, and then map that hot key to a mouse button, which is how I used to activate Mission Control. For $18, is well worth it.

This further points to software, as clearly the hardware can handle it when done correctly. Hopefully this will be addressed by Apple in a future release, but in the meantime, TotalSpaces works just fine.

Thanks,

- Scott -

This is bogus.

I have the M295X and 32GB of RAM and the pure SSD (no way you can blame I/O performance) I have transparency off and I've had to quit using Mission Control/Expose completely. Which *****, because those features are what drew me to OS X from a productivity standpoint back in 2004. Expose sold me on OS X, immediately. Now between Apple borking it completely in one of the dot releases and this iMac, I've gotten used to life without it and I'm only marginally more productive on OS X.

I don't know if it's apple's fault or ATI but this is embarrassing and I feel like a boob for being an early adopter.

Today's hardware (especially the wet blanket M295X) is not going to push animations at 5K without a lot of optimization work and that shows. In between the lag, stuttering and severe video tearing there is no way this machine (over $3000) is going to age gracefully.

Once we hit the second revision, hopefully we have a new OS release and apple runs back to nVidia. I'll sell this one and take the hit for a working computer.

I have the base model (i5, mx290, 8GB, 3TB Fusion) and this mission control issue is simply horrible.

Expose not working is almost a deal breaker for me... please Apple, fix this!!

(there are also other graphic issues like stripes in iPhoto but Expose/Mission Control is by far the most important in daily work, so annoying)

I submitted a bug report for this issue using Apple Bug Reporter in December and they now asked me for another sysdiagnose with 10.10.2. I think with 10.10.2 the whole UI does not become laggy anymore bug Mission Control and several other apps are still shuttering. If you also have these issues with your iMac please submit a bug report, this will help Apple to fix the bugs. https://bugreport.apple.com/

the Mission Control UI still lags & stutters on my iMac, running 10.10.2. i already submitted a bug report. hopefully this glaring bug will be fixed in 10.10.3