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OS X Lion is incredibly slow (even after index)

I've installed Lion on my iMac (24-inch, Early 2008, 3.06GHz Intel Core 2 Duo, 4GB RAM) and it has become INCREDIBLY slow. I've heard many people saying that the machine would return to its typical blazing speeds after indexing finished, and it has — I've left it on overnight a couple of times to make sure everything finished, and it's still much slower than it was while running Snow Leopard. Virtually every application hangs — when typing in Finder (for example to rename a folder) the text lags several seconds behind what I'm typing. Mission Control is terrible — the graphics lag behind and it takes several seconds for the animation to finish. Often the animation doesn't appear at all, and it just flickers between frames awkwardly until the mission control display finally appears.


I'm working on backing up all my data and doing a clean install … I'll see what happens, but if it doesn't work I'm going to have to roll back to snow leopard, because this is ridiculous. I've never seen an OS change slow down a machine so much since Vista … hopefully it's fixable. Any thoughts on what might be the cause?


(Oh, and activity monitor scans look normal … nothing's hogging the CPU, and there's slightly less than 2GB of RAM free almost all the time.)

iMac Core 2 24, Mac OS X (10.7)

Posted on Jul 23, 2011 11:59 AM

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288 replies

Apr 6, 2012 7:40 AM in response to jswin

I think I accomplished the same thing, but inadvertently. By installing a new disc (in my case an SSD), the clean install created a new preferences file in the new user folder.


Since I also reinstalled all my software, there would be no left-over preferences. Maybe I received the benefit you speak of but didn't know it!

Apr 7, 2012 7:52 AM in response to jswin

I have an iMac 24" 3.06ghz Core 2 Duo with 4 GB Ram and Lion runs like a turtle. I did a clean install, wiping my hard drive and it ran ok, but it was way slower than 10.6. After fixing permissions and the wonderful pinwheel of death, I returned to 10.6.x and my stable, fast machine returned.


As an IT engineer, my conclusion is the Lion barely functions on a core 2 duo. What is really sad is Window 7 flies on this machine and is extremely stable. I believe many of you that have posted in regards that you are tolerating Lion. I find it hard to believe that your Core 2 Duo machines are truely flying. We have Dual Mac Pro's with the same chipsets and they also experience the slowness.


My recommendation is to revert to 10.6 or buy a new machine.

Apr 8, 2012 6:32 AM in response to jswin

I was browsing the internet on my MacBook Pro - watching a youtube video

When suddently after closing full screen mode my computer froze. There were notning I could do.

I did a hard reboot and now my finder runs extremely slow. I am trying to backup the inportant files, but whenever I click with the mouse finder goes crazy and the rainbow ting starts to spin for seertal minutes.

Apr 13, 2012 8:25 PM in response to jswin

Just in case it might help others, I too experienced extremely slow peformance issues with my new iMac 27", including launchpad freezes, and nothing appearing in "All Files" within File Finder. Tried many things, including the permissions repair, disk verification, etc., with no luck and constant beach balls. Figured I'd limp along with it until I was able to take it to the Apple Store. I happened to notice that my network storage device had stopped responding, so I rebooted it, which ended up resolving my all of my original issues.

May 5, 2012 11:33 AM in response to APierce24

AP24 - You are my new best friend! Thank you so much for taking the time to share this remedy with others. It worked!! It's highly likely that because of you I did not pull out every single hair on my head or hurl my computer from the balcony of my home. Prior to going on the community forum, I tried every keyword I could think of to find some help on this in Apple's Home Page 'Support' (or non-support if one were being honest) section, but to no avail. I knew it had to do with the download of Lion and tried everything I could think of to fix it but again, nothing. I normally go to user groups first, but for some reason this time did not. Lesson learned.


Again, thanks for taking the time to share this.

May 28, 2012 11:58 AM in response to jswin

Lion was unuseably slow on my 2008 MacbookPro Core 2 Duo. Slower than a G3 machine. I didn't have the patience for a clean install and restore, and also needed another machine capable of running some older apps (Canvas X)--so restored to a 10.6.8 Time Machine backup and the machine is flying. IMHO, don't bother with Lion and go back to SL until they get release a proper update (Mountain Lion??).

May 29, 2012 11:38 AM in response to Fmontone

Thanks for posting this, Fmontone. Resetting the PRAM solved my performance problem. I had already tried repairing permissions, and moving all files from library, adding back the ones I needed. I was getting ready to do a clean install, when I tried resetting the PRAM, and that solved it.


My symptoms where a generally slow system, even with lots of free memory and idle CPU.

May 29, 2012 6:36 PM in response to CuriumUmulium

Resetting the PRAM is not a permanent solution. It "worked" for me 2 months ago, now I'm back to square 1.


None of the tips mentioned here will work. Disk permissions, deleting a couple of old PLIST files, redoing font caches, etc etc.


All the funky tips in this thread -- I've read through all of them, and done all of them. Been subscribed to this thread for over a year now. Many colorful suggestions.


NONE works. I called Apple, and their official line is clear: format everything and reinstall OSX Lion afresh. That's the only lasting solution.


I cannot do that immediately as I have a LOT of configurations and data. Even with Time Machine, a number of personalized details such as server configs etc are not carried over, and I'm concerned Time Machine will also carry over all the settings that are causing these issues.


So, only solution, unfortunately -- backup all data, all configs, all apps etc, and reinstall the beast.

May 29, 2012 7:32 PM in response to Cyberpundit

Time Machine is likely your problem. Buy a Passport for Mac or other backup unit. Redo a Time Machine backup. On the new device Then reformat your current backup device (Time Capsule or other). My Mac was trying to do a Time Machine save but was blocked by some incompatibility from previous SL and Lion. This solved my issue instantly! Reverted to backing up on my Time Capsule and all is perfect! I was seriously considering throwing my Mac out the window for a while. This was not a temporary fix...it's been over 2 months. Good luck!

OS X Lion is incredibly slow (even after index)

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