Many forums say, that enabling Increase Contrast option in Accessibility Preferences helps Yosemite to make the animations, like entering Mission Control to be much smoother. This is also consistent with my experience.

Increase Contrast off: https://www.youtube.com/watch?v=ctOj1U4OZio&index=3&list=PLsZWReFinrU5GLvs7ILwGvAVTICcjLhTD

Increase Contrast on: https://www.youtube.com/watch?v=BNac3VPZDKI&index=2&list=PLsZWReFinrU5GLvs7ILwGvAVTICcjLhTD

What I am interested in, debugging what causes the general slowness of Yosemite interface. It is clear, that at least one of the reasons is canceled when I turn Increase Contrast on. Common sense says, that Increase Contrast turns on Reduce Transparency option too, so it might be the reason, because calculating the transparency of the semi-transparent layers is a hard thing to do. This is not the case, because enabling Reduce Transparency only has no effect on the speed at all.

So the question is: what does Increase Contrast switch? Some GPU parameters? Less textures? Using other rendering algorithms? Something has to be.

  • How many menubar apps do you have running? I found that the jankiness of Exposé and Mission Control animations (without Increase Contrast) was directly proportional to the number of apps I had running that put an icon in the menubar. If I quit every single one of them, then the animations are as smooth without "Increase Contrast" as they are with it turned on... I normally run with around eight extra menubar icons over the standard clock, wifi indicator, etc. – Matt Gibson Sep 10 '15 at 21:35
  • @MattGibson: It is not related. Lagging happens in fresh install too. El Capitan will fix the issue. – gklka Sep 10 '15 at 21:36
  • Interesting. (It seems to be clearly related for me, on my 5K iMac, but I'm guessing there may be a bunch of different factors having an effect on this.) – Matt Gibson Sep 10 '15 at 21:39

I can't comment specifically on the Contrast setting, however there are various defaults you can enable from the terminal that will speed things up - specifically window "show" delays.

Browse some of these scripts:

You will find various commands to reduce the delay between showing windows,


To speed up mission control you could do:

defaults write com.apple.dock expose-animation-duration -float 0.1
killall Dock

This will reduce the animation delay to .1 second before showing mission control

Its possible some of these settings get tweaked when you go into enhanced contrast mode.

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  • Thank you. I know about these, and I want to keep OS X's default behavior if possible. The problem is that on some machines (like on Retina MacBook Pros with external displays) it is very slow. Reducing the animation length does not help it just skips the animation entirely. That's not what I want. – gklka Jun 3 '15 at 17:56
  • Are you using VGA, HDMI, DIsplayPort, DVI? That "could" have an impact. You can also consider closing the lid on your mac and using "Just" an external monitor - of course you would need a keyboard and mouse as well then. – Jeef Jun 3 '15 at 17:58
  • DVI and Thunderbolt, it does not matter, I have tried it. Using less screen estate definitely helps, but I don't want to waste my beautiful Retina screen of my MacBook Pro :) – gklka Jun 3 '15 at 17:59

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