iMac (model 2009, purchased in late 2012) sometimes becomes extremely slow. I've opened the "System monitor" and discovered that there is a huge lack of RAM.

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But as you can see there is no app occupying all the memory (except the kernel_task, i've got no idea what it is). The 2nd pic show that CPU is alright.

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I've tried to make "sudo purge" and it helps a little, but a few minutes later lags come back. I don't want just to get more memory, coz I don't understand why 4 GB isn't enough when the largest app - Photoshop - uses only 179 MB. If you got any idea what can be the reason you're welcome.

p.s. Sorry for the pictures are on Russian, but I'm sure it won't be a big trouble). If necessary, i can give any screenshots.

1 Answer 1


The memory pressure (yellow part at the bottom of the first screenshot) so I recommend upping your ram to at least 8 gigs of RAM (or even 16 if you can afford it). To see what kind of RAM you need, see HT1423 .

  • 1
    The question is not "How much?" but "why?". I can't find the reason of memory compression. Commented Dec 8, 2013 at 17:51

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