(Excuse the crossposting to hardware & software as I'm not sure if it's hardware or software...)
Got a very weird problem and I'm looking for suggestions:
It's a friend’s “Mid–2012” 27 inch iMac with 8 GB of memory.
If I said "it is running slow” that would be the understatement of the year. Almost everything you do results in the spinning beach-ball Wait cursor. Even something as simple as choosing “About this Mac" without any apps running results in a delay of almost a minute before the window opens!
Everything does seem to work but so slow as to be really unusable.
Here's what I've done in the way of trouble shooting so far:
1. Scanned the computer for viruses and malware. None found.
2. Used disk utility to check the disk (APFS formatted). OK.
3. Checked SMART status returned by disk — no trouble reported.
4. Used Onyx to run maintenance scripts, cleaned and rebuilt caches.
5. Checked the launch control files, the extension folders, and startup items to see if anything was running in the background which shouldn’t be. Nothing abnormal found.
6. Used activity monitor to check memory usage, disk activity, network & CPU usage. NOTHING is consuming much resources!
7. Ran the Apple hardware test utility. No hardware issues reported.
Am I missing something?
At this point, the only thing I can think of remaining to do is to reinstall the operating system.
Have you set up a clean log-in identity? If not, try it and see how it runs from a clean identity. If that fixes it, I'd bet it's something in the Prefs folder. I had to move my entire prefs folder to the desktop a few months ago to trouble-shoot a similar problem. Drove me nuts.
"I really need a new tagline"
—P M Evans
Thanks Phyllis -- I'll try that.