I have an old iMac for the kids: iMac 8,1 Core2 Duo with 3GB (2+1) RAM that was recently upgraded it to Mavericks 10.9

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It's running quite slow; free RAM is always pretty low. Apps run "OK" once open; it's mainly switching between apps, loading apps, and booting up which take forever.

My question is how can I know if installing a 120 GB SSD (lying around) likely give me significant performance boost or if instead I need to upgrade RAM (which will cost me)?

I replaced with SSD -- seems faster -- but follow up here: Best version of OSX for 2008 iMac?

  • What runs slowly - an app - or switching apps or loading files?
    – mmmmmm
    Commented Mar 8, 2014 at 20:21
  • @Mark, mainly switching/loading apps, I would say. Once an app is running, it's not TOO bad.
    – d0g
    Commented Mar 8, 2014 at 20:28
  • One question per question is best. This could be a) how to diagnose if RAM is needed/constrained? b) what older OS for a Mac that is RAM constrained? c) guess how much RAM is needed assuming this mac is RAM constrained.
    – bmike
    Commented Mar 8, 2014 at 21:45
  • I have a question. Why can't you do all of them? Commented Mar 10, 2014 at 14:09
  • 1
    What color is the memory pressure graph in Activity Monitor when you see the slowness? (or would you be open to an answer that goes into how to measure if IO or memory is the culprit for observed slowness.)
    – bmike
    Commented Mar 10, 2014 at 20:07

1 Answer 1


According to your comment, it looks as if you could do better with more RAM. If it was just launching slowly, then I would say the SSD, but since its switching apps also, I think more RAM would be nice. Unless your iMac ran a lot better under Mountain Lion or below, I really wouldn't downgrade.

BTW: Don't disable the user accounts. Just log off when you are not using that user account.

Since you have a spare SSD, you could also just connect it externally using an inexpensive USB to SATA adapter and install new OS on it and run some A/B tests. You won't see the full speed of an internal placement - especially if you use USB 2.0, but it's often enough to know rule out RAM or OS as a cause of slowness.

  • I don't think booting off an SSD via USB2.0 would be even remotely similar to installing it internally... I'm sure the internal drive, slow as it might be, is faster via SATA than any USB2.0 connection...
    – d0g
    Commented Mar 11, 2014 at 0:16
  • Actually, it will be slightly faster. I'm not saying that it will be equal to an internal SSD, but it will be a definite improvement. Looking at this thread (apple.stackexchange.com/questions/19402/…), I think you will see a boost. Commented Mar 11, 2014 at 0:52

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