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Very puzzling iMac performance problem
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Jedi Knight
Picture of Steven J Gold
AIM: Online Status For StevenGold
posted
(Excuse the crossposting 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.
 
Posts: 234 | Location: Oak Park, MI | Registered: June 11, 2002Reply With QuoteReport This Post
Padawan
Picture of Wolfman
AIM: Online Status For wolfman090
posted Hide Post
I have the same problem with my 21.5".
Took it to the Apple Genius bar today. They ran every test imaginable but could not come up with a solution....Said I should do a clean install and see what happens....
 
Posts: 61 | Location: Troy, MI 48085 | Registered: February 25, 2004Reply With QuoteReport This Post
iBBS Addict
Picture of James R. Cutler
posted Hide Post
quote:
Originally posted by Steven J Gold:
... It's a friend’s “Mid–2012” 27 inch iMac with 8 GB of memory.
... Everything does seem to work but so slow as to be really unusable.
... Am I missing something?
...

You missed some data important for diagnostics:
What storage media? 5400 rpm spinning rust, fusion, etc.
What is the source of SMART data ok? Apple's "SMART Verified" is inadequate.
What macOS version is installed?
What did your friend last change/update. (When was the problem first observed?)
Have you checked if the CPU is being throttled because of high temperature? (Cold Boot)

One suggested on-site diagnostic would be to boot from a thunderbolt-attached SSD with a clone of the internal boot volume and recovery partition and/or a fresh macOS install. This is somewhat simpler than reinstalling on the internal drive just for diagnostics.

.

This message has been edited. Last edited by: James R. Cutler,
 
Posts: 1964 | Registered: January 02, 2003Reply With QuoteReport This Post
Jedi Knight
Picture of Steven J Gold
AIM: Online Status For StevenGold
posted Hide Post
James --
10.13.6.

Internal 5400 rpm HD (about 50% full), not fusion.
The problem has existed almost a year so if the disk was failing I'd expect by now it would be total toast and even Apple's stupid SMART would notice. Also, checking the file system comes up clean.

CPU not hi-temp throttled; the fans are working normally (hardware diag confirms) and the response is horrid even with the CPU utilization reported at 10%.

She's up to date on updates, and when she first complained to me, she was on Lion!

Her machine only has Thunderbolt 1 (and I don't have any portable TB drives but I will try booting from an external USB to see what happens.

Cloning the internal drive while booted from it using something like CC is out of the question -- her system is so slow it would take several days to complete and since she's paying me (she insists as she uses the computer for business) by the hour it would take many days and cost too much.
 
Posts: 234 | Location: Oak Park, MI | Registered: June 11, 2002Reply With QuoteReport This Post
iBBS Addict
Picture of James R. Cutler
posted Hide Post
Based on your input and my experience, my next steps would be:

  • Create a test Mojave system on an APFS SSD.
  • Put the SSD in an external enclosure with USB 3 or FireWire 800.
  • Boot and confirm the test system using one of your machines.
  • Boot the client system using using the test system.

The results will speak for themselves.

Side comment:
Spinning drives can be well into failing without any indication in Disk Utility, which does not check specific SMART parameters like Reallocated Bad Sectors, which are a strong indicator of impending failure.
 
Posts: 1964 | Registered: January 02, 2003Reply With QuoteReport This Post
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