iMac painfully slow

Specifically, these performance numbers for your Fusion system are abysmally low:

Performance:

System Load: 1.67 (1 min ago) 2.00 (5 min ago) 1.92 (15 min ago)

Nominal I/O usage: 0.84 MB/s

File system: 131.90 seconds (timed out) ⚠️

Write speed: 12 MB/s ⚠️

Read speed: 47 MB/s ⚠️

For your iMac model, those should be:

Write speed: 600-900 MB/sec

Read speed: 1300-1800 MB/sec

The time-out failure for File System indicates a severely sick storage array, but does not tell us which of the two Fusion components is at fault. I suspect the mechanical side. That reduction drive speed is far more than was shown in previous report where CMM reduced drive speed.

Whether CMM has bothered your other computer or not is a moot point to me. They hype their product as needed for doing what Apple already does with their automated periodic maintenance system. That's just wrong. Fear marketing.

It's really time for a new computer, it does not make any sense to spend money on such an old machine. It is obsolete and Apple considers it Vintage meaning parts are not available. Have you considered that option?

Please do the following and we can look for obvious issues.

It will help us get a good idea of what is causing your problem if you provide a report of your system, that way we do not have to play 20 questions with you. The report we are requesting does NOT provide any personal information and is extremely safe to use. Please navigate towww.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again. 

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click How to use the Add Text Feature When Post… - Apple Community It is helpful to us if you download the report to your Desktop.

Well there is quite a bit wrong with the computer.

I see some issues in your report. First is you have CleanMyMac installed which is considered malware by most experienced users on these forums. Mac OS is catlike in that it cleans itself, Mac OS does not benefit from nor does it require any of the following types of third party apps:

·      Antivirus Apps

·      Cleaning Apps

·      Security Apps

·      VPN Apps

·      Maintenance Apps

What these types of apps do is the exact opposite of what users want. They make Mac OS slow, appear buggy, can damage Mac OS and sometimes create unwanted behaviors. In short, they are really bad news!

So the first order of business for your computer is that you need to locate the developers. uninstall instructions for CleanMyMac and please uninstall CMM. Because CMM is pretty nasty stuff it tends to leave parts behind after being uninstalled, a testimony to how poorly written the app is! To fully ensure you have uninstalled it please download the free version of FindAnyFile directly from the developer. Then have it search your system for the following:

·      CleanMyMac

·      MacPaw

Have it Trash any files with those names in them and then ensure the Trash is empty. 

Next, there is an indication that the hard disk portion of your Hard Drive is failing! To be sure, download DriveDX and test the HD. If any errors appear that simply confirms what the EtreCheck report is indicating.

If the HD is failing then I'd recommend simply replacing the computer as it is now obsolete, parts are tough to obtain and well a new Mac will dramatically improve performance! Finally there is ZERO evidence that you backup this computer which means all of your data will be a loss if you do not backup! If you are not familiar with Time Machine then please read Back up your Mac with Time Machine

Running CleanMyMac has no impact, as also restarting it.

Running CMM could be part of the problem. That unneeded app has caused slow performance in other "slow" reports here. Catlike, the macOS has cleaned itself for near a quarter century. macOS includes elegant, automated self-maintenance routines that do ALL needed housekeeping as often as daily, including defragging if needed. It needs no outside "help."

Adding so-called "cleaning" apps can conflict with the elegance you paid Apple to build into the OS.

+1 on the EtreCheck report. Among other things. It will tell us what storage type you have, important because storage issues are the #1 cause of slow iMac reports here.

Yikes, get backed up asap.

OK, best of luck my friend.