Yosemite very laggy after installation

My issue is not fully resolved with disabling the transparency, though it does help a lot.

Like Jessie, I too performed a fresh install over the weekend as a test. The issue is still apparent when plugging in an external. Not sure if I can afford taking the time to go back to Mavericks, although things did run beautifully.

Anyone have any updates from Apple on a potential fix?

hey. i think i found a solution but it does require backing up all your work.

the problem is is that you may have installed mavericks on mountain lion, and Yosemite on mavericks, 3 layers of OS X does cause lag, doing a clean install should solve this problem for you

You need to do a clean install by downloading a fresh copy of Yosemite on a (minimum 8gb) usb drive and then delete everything and start from scratch. click here to get a step by step: http://osxdaily.com/2014/10/18/clean-install-os-x-yosemite/

hey. i think i found a solution but it does require backing up all your work. the problem is is that you may have installed mavericks on mountain lion, and Yosemite on mavericks, 3 layers of OS X does cause lag, doing a clean install should solve this problem for you You need to do a clean install by downloading a fresh copy of Yosemite on a (minimum 8gb) usb drive and then delete everything and start from scratch. click here to get a step by step: http://osxdaily.com/2014/10/18/clean-install-os-x-yosemite/

Hello,

I already tried that - no success. Do you have an AMD 6490M ? Chances are you do not, and are having separate issue than a few of us with AMD 6490M chipsets on Yosemite.

I spent the time to format and clean install Mavericks, and it's back to running great, I wish the same was true when I tried Yosemite.

If anyone sees progress with AMD 6490M reported issues, please update this thread!

Anyone find a formal fix using the AMD 6490M yet?

Something interesting happened to me the other day. I had the computer docked to the thunderbolt display, closed the lid, reopened it and finder crashed. I got an error report saying there was a critical graphics error. Everything refreshed and the desktop came back on. Since then, I have had 0 lag, like when I was using Mavericks. It's as if there was a cached driver file that needed to be flushed, and then the correct drivers were loaded. Wish I could explain how to reproduce, but it was completely random from my point of view.

I'm having the identical problem you did with the same hardware. Tried closing the lid and reopening but did not get a graphics error/crash. Would be great to find out what it actually did to clear it up and whether the problem reappears.

Just adding my name to the list - same AMD Radeon HD 6490M 256 MB graphics as others have reported. Runs fine without the TB Cinema Display, but like a dog when its connected.

Try removing Backblaze.

I had no problems in Mavericks. After upgrading to Yosemite, I was getting constant beachballs with Carbonite installed. Deleted it, and beachballs went away. Installed Backblaze. While doing the initial backup, I get the beachballs, but when I pause it... no beachballs.

My guess is that these online backup processes might be causing problems in Yosemite (or on fusion drives, like in my iMac).

Had same problem: MBP mid 2014 + 2yr old Thunderbolt display. Note: my MBP came with Mavericks, was upgraded to Yosemite.

Problems I had: huge lag when switching between spaces, lag and dead slow window resizing, effects like combo box selection was almost as being slow motion, etc... was very slow. Still, Activity Monitor did not show any "drag" (CPU usage), nor did the other hints (like disabling transparency) help at all, lag was always same. One thing I noticed: in clamshell and two-monitor mode (MBP open), Thunderbolt display was laggy, but when MBP used w/o display, it was okay, not laggy.

I went for solution recommended by user "smazurov" few responses below: reset SMC

Intel-based Macs: Resetting the System Management Controller (SMC) - Apple Support

Now the switch between spaces, window resizing is snappy as I'd expect...

New firmware update came out today for Thunderbolt Display. Guess they were waiting for 10.10.1 to release first. With the new firmware and turning on Reduce Transparency, disabling auto-switching graphics card it seems to be better now on my setup especially with zooming. However not as good as it used to be before Yosemite so clearly not completely resolved (in my case).

Those updates haven't fixed the issues. I did a clean install of Yosemite. Not only I am experiencing lags but also graphic glitches very bad. I agree with dapvincent. In Mavericks no problems, and that system of mine was upgraded from Lion to ML and then to Mavericks; it also has many more applications installed compared to the clean installed Yosemite.

Does someone knows if it is possible to use previous (Mavericks) AMD Radeon HD 6490M drivers on Yosemite?

Same here with 10.10.2 . MAcbook early 2011 was perfect with mavericks, very very laggy with yosemite.

Unbelievable.

I have an early 2011 MBP with the 6490m and am having the same issue. Going from 4GB to 8GB seemed to help with the integrated card... I hope it is not an unresolvable VRAM issue.

I have 16gb of ram and an ssd... and it is very laggy, 10.10.2 now.

What @plindelauf has said is exactly the problem I'm having and exactly my observation. As soon as an external screen is connected to my 2011 Macbook Pro the graphics switch to the AMD Radeon HD 6490M. Once that happens it's not long before there is considerable lag when switching between applications and tabs. The UI animations, normally smooth are barely visible as the graphics try to at least render a few of the frames before the transition is over. Window dragging is also extremely laggy.

I don't recall this being an issue in versions of OSX prior to Yosemite. I have ticked all the boxes of the first things to try (reset pRAM, SMC etc) but nothing fixes it. I agree that a driver update from Apple may be our only hope. How do we get Apple Support's attention on this?