iMac is running extremely slow after clean install

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iMac is running extremely slow after clean install

I have a 21.5" late 2015 iMac that I've been having trouble with. It's very slow, and beachballing on a regular basis, startup is extremely long - you get the idea. So I backed everything up, formatted the drive and did a clean install. But after the clean install and before installing most of the applications I had on there before, I noticed that the startup still takes forever and that the whole thing is running really slow again. Tried First Aid, Diagnostics - nothing to show.

I tried running Etrecheck and the results were inconclusive. I've attached the report below.

Etrecheck Report

I also found a diagnostic script written about in this post and ran that. Those results are below

Diagnostic Script Results

If anyone has any ideas on how I could speed this thing up, I'd appreciate it. Thanks!

iMac Line (2012 and Later)

Posted on Apr 27, 2021 8:21 AM

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Answer 1

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Jack-19

Level 8

45,872 points

Apr 27, 2021 9:36 AM in response to forestspringscreative

Hi there,

The reason your iMac is very slow is due to the 5400 rpm hard drive. Very slow. If you use an external SSD as your startup disk and run macOS from that, it will make your Mac 10 to 20 times faster for storage. For more info, instructions, and what SSD to buy, please read: https://discussions.apple.com/docs/DOC-250003583.

Cheers,

Jack

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iMac is running extremely slow after clean install

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