Help me fix a slow Mac!
January 10, 2011 6:01 AM   Subscribe

How do I fix a slow iMac?


1. I updated to OS X 10.6.6.

Immediately boot times were insanely slow and when the system finally booted all apps loaded slow, got beachballs on every mouse click, and it killed Thunderbird 3.1.7 (crashed on load; profile fixes did not work).

2. Long story short: after numerous fix attempts I had to restore from Time Machine. Today I worked on the box: I reverted to Thunderbird 3.1.6, which worked; I combed through the files, purging orphans; I killed Spotlight, which seemed to speed things up a bit; I reset PRAM and NVRAM; I ran OnyX to clean everything, fix permissions and verify the drive (OK).

Boot times are much shorter now, but the system still lags. Apps take far too long to open, and I have left Spotlight disabled.

I've Googled everything in the book but nothing seems to bring the system back up to speed.

Any ideas?
posted by bwg to Computers & Internet (15 answers total) 10 users marked this as a favorite
Do a time machine backup and install Snow Leopard from scratch?
posted by jedrek at 6:07 AM on January 10, 2011 [1 favorite]

How much ram do you have? (maybe do a system info to be sure it's all working ok)
posted by bonobothegreat at 6:28 AM on January 10, 2011

Sounds like your hard drive's on the way out. The verification/repair options are good for system-related drive issues, but they're worse than useless if the drive's mechanically failing. I've seen more drives than I care to count report that they're a-O.K. even while they're violently clicking and vibrating like crazy.

I'd wipe the drive, reinstall the OS but hold fire on restoring your backup — see how the machine runs in a pristine state. If it's still slow, it's almost certain to require a hard drive replacement. A quicker way to check this might be to find a spare external drive that you can install OS X too and boot from. It'll save you running in circles with the internal hard drive.
posted by jaffacakerhubarb at 7:23 AM on January 10, 2011

Seconding jaffacakerhubarb. Boot times should almost never be slow, unless something is massively wrong. Hard drive is the most likely culprit.

Open up Disk Utility, and look at your hard drive's S.M.A.R.T status. If it says 'Verified,' the disk is probably OK. If it says 'Failing,' back up your data NOW, and go buy a new drive. Do not attempt any of the 'Repair' options if your disk is physically failing, as this will stress the disk, and won't fix anything.

If you have one of the oldest possible iMacs that Snow Leopard will run on (circa 2006), it probably came with 512MB of RAM, which will definitely slow things down, but not to the point of being unusable. However, if you've only got 512MB, you really should consider buying more RAM.
posted by schmod at 7:44 AM on January 10, 2011

I recommend the following,

a) Replacing the harddisk with a SSD drive. You can get a good SSD drive (around 80 or 90 MBs) with Sandforce firmware for about $100 these days. Make sure you get a SSD drive with the sandforce firmware.

b) Install additional memory. Ideally, you will want to max out the memory supported by your iMac. I recommend using Crucial memory's website to find the correct type of memory supported by your iMac.
posted by jchaw at 8:13 AM on January 10, 2011

Nthing the failing hard drive. In addition to SSDs, Seagate has finally started shipping hybrid drives (standard drives with flash cache) in the Momentus XT line, so those are an option as well. They're 2.5" drives though.
posted by chairface at 8:27 AM on January 10, 2011

Best answer: jchaw: I will never understand people who recommend dropping to a sub-100 gb drive for a desktop machine. When you aren't worried about battery life, going with a large-capacity high RPM drive is a smarter move.

bwg: You could check your memory. I have no problem running Tbird 3.1.7 on a nearly 4-year-old MacBook Pro with 4 gb RAM. It runs (s-l-o-w-l-y) on a seriously aging Mini with 512 kb RAM. But it should run on your system just fine - if my old-ass PowerPC can make it go, your Intel iMac ought to have no problems. I would suspect memory MIGHT be an issue but I would lean toward the drive. If so, my suggestion:

Step 1 is to grab your Snow Leopard/Leopard disk. Start the iMac from the disk (insert DVD, hold down option when rebooting, choose the DVD when the boot menu shows). You'll get the standard install menu. Close the installer, then run Disk Utility from the system menu. Check the disk for errors (validate and repair if necessary).

Step 2 is to replace the disk. Hard drives are cheap and it's better to be safe than sorry. Figure out what size disk your machine uses, and get the biggest, fastest drive you can fit. You can find iMac HD replacement step-by-step guides at Note that you may need some funky Torx screwdrivers for some steps. If so, the iFixit guides helpfully include (self-serving) links to places you can purchase those.

You can either clone your existing drive (for which you'll need an external enclosure, FireWire preferably) using SuperDuper (clone, then swap - it should boot up with no issues), or you can just swap in the new drive and restore from Time Machine (for which you'll need a working computer). Boot the system from the OS install disk, and follow directions from Apple here, noting the caveat listed here for restoring existing data to a brand new empty drive (old but may be necessary - sorry, Gizmodo link.).
posted by caution live frogs at 8:51 AM on January 10, 2011

If the iMac is early 2006, like mine, then replacing the hard drive is not easy. Apple made later models easier to upgrade. I've increased my RAM and turned off all visual effects I can (like the genie effect), and while it might not help startup it makes things run better. Also, check Accounts in system preferences, and look at your login items. There may be lots of things in there you don't need.
posted by monkeymadness at 10:04 AM on January 10, 2011

Boot in verbose mode (cmd-v at chime), look for disk I/o errors. Or grep through the system.log in Console for "I/o"
posted by now i'm piste at 10:22 AM on January 10, 2011

Response by poster: Thanks for the replies so far.

Don't think it's the hard drive; the thing is only two years old, no noise or clicking. Disc has been verified several times both booted and via DVD.

Model Name: iMac
Model Identifier: iMac9,1
Processor Name: Intel Core 2 Duo
Processor Speed: 3.06 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 6 MB
Memory: 4 GB
Bus Speed: 1.07 GHz
Boot ROM Version: IM91.008D.B08
SMC Version (system): 1.45f0

I have not yet booted in Verbose; I plan to try that although I will probably have no idea what I'm looking at (not a computer wizard). If I do see errors, what's the way to fix them?

During my recovery attempts I did try a fresh install of Snow Leopard and added the combo update of 10.6.6, and that had no slowdowns at all, leading me to believe this is a software issue. However Thunderbird was still inoperable and I spent quite a long time trying to determine what in the profile was causing it to crash. 3.1.7 would not work on 10.6.6; it was only after restoring and installing 3.1.6 that I got my mail back.

I was really hoping to not have to start from a fresh install and spend yet another day reinstalling software and tweaking. If it comes to that, is there a way to install on a separate partition and migrate all my settings?
posted by bwg at 4:48 PM on January 10, 2011

How about creating a new user file? Log in as that user, install Tbird abd see if it works. If it does, the problem is specific to your profile and not the machine. If so, try starting Tbird in your profile in safe mode (I forget how to do that on a Mac; command-line flag I think?). Or delete / move the /Users/(User name)/Library/Thunderbird/profile folder to force creation of an entirely new profile on start. If it's a profile issue or a problem with an extension that should work; you can make the safe mode settings stick (ie, everything extra in the program is disabled) and work backwards from there, turning extensions on one at a time to see which extension/setting is the problem.
posted by caution live frogs at 5:45 PM on January 10, 2011

I hate to say it, but this incarnation of iMac is really susceptible to fried ass hard drives (our lab had to replace two HDs in two separate iMacs of this model just this fall).

Honestly, it's a foolish design. Cramming the power source into that oh so appealing frame was a bad decision.

After you replace the HD (cause it's almost inevitable, I would imagine), install SMC Fan Control so that you can turn the fans up higher and hope the next drive can take the heat.

Good luck!
posted by solipsophistocracy at 9:36 PM on January 10, 2011

Don't think it's the hard drive; the thing is only two years old, no noise or clicking. Disc has been verified several times both booted and via DVD.
The hard drive on both my work iMac and my home iMac also passed verifications several times right before failing entirely. Each computer presented the very same symptoms you're having.
posted by notbuddha at 9:08 AM on January 11, 2011

Response by poster: The system seems to be running faster now but still not as zippy as I'd like. I think I might invest in a new HD just to be safe.

Thanks all for the suggestions.
posted by bwg at 4:28 PM on January 11, 2011

Mac OS X handles bad sectors amazingly stupidly, essentially hanging the whole machine while repeatedly rereading that sector to obtain the data. And the SMART status being verified doesn't necessarily mean the drive doesn't have issues that'll make sectors not read correctly the first few times.

If you ever see a spinning beach ball, you should immediately type "sudo dmesg" in terminal or fire up Console. If it's complains about any specific file, try "sudo mkdir /.badblocks", then "sudo mv [bad file] /.badblock", and then recover the original file from you time machine backup. And obviously exclude the /.badblocks directory from spotlight, time machine, ccc, etc.

In this way, you'll ensure that the machine never again tries accessing that file containing iffy blocks. If you find many files cause this problem, then you best just replace the drive, even if the SMART status is sill verified.

If you're still on warranty, there might be ways to get the SMART status to fail quicker, thus buying you an on warranty repair. I'd try running verify disk from Disk Utility and repeatedly accessing the bad files form a script.. after backing up all your data of course.
posted by jeffburdges at 6:57 AM on February 16, 2011

« Older I guess I shouldn't be surprised that...   |   Scuba in Tunisia Newer »
This thread is closed to new comments.