2019 iMac (Retina 4K, 21.5") - sluggish - ran ErteCheckPro Report

First issue is that you have a failing hard drive, make a complete backup immediately and take your iMac in to have the hard drive replaced. Waiting till your iMac will no longer start will only make things worse if you’re not backed up.

After the hard drive is replaced uninstall Clean MyMac, it's not needed and will only slow your iMac down until it becomes unusable.

I've seen several cases here where removing CleanMyMac improved disk performance in EtreCheck reports, even removing the failure warning. Completely uninstall CMM per the developers' instructions and then run another EtreCheck report.

Still, the 3GB/sec, 5400rpm hard drive is going to be the bottleneck in that model. Without CMM, it should a little less of a bottleneck but you won't have a speed demon.

These drive read/write numbers:

Performance:

System Load: 2.04 (1 min ago) 1.66 (5 min ago) 1.48 (15 min ago)

Nominal I/O speed: 4.65 MB/s

File system: 121.35 seconds (timed out)

Write speed: 24 MB/s

Read speed: 44 MB/s

should be in the 60-70MB/sec range on a computer without dungware.

Your first problem is you installed Clean My Mac. Every time I've ever seen it it was only making problems worse. Uninstall that per the developer's instructions.

Your second problem is you are running Catalina off the anemic 5400rpm laptop HDD Apple shipped by default. Those are kinda slow on clean installs and only get slower as 3rd party software is added. I'd strongly suggest investing in an external USB-C SSD and reinstalling or restoring MacOS onto that.

CleanMyMac X.app

That is your primary problem. CMM is considered by most here to be akin to malware. Do a Google search to find out how to uninstall it according to the developer's instructions.

Then rerun Etrecheck and see if it still says you have a failing drive. Removing the offending software sometimes has removed that failing drive report. But make sure you have a current and full backup of your drive!

Another thing going against you is that your Mac model is the slowest that Apple sells: 8 GB RAM and a 5400 rpm hard drive. With that setup you should limit the number of apps open at one time to 1if at all possible.

If you are still in the 14 day return window returning it and ordering a more capable model is a solid alternative.

The 3.0GHz model is actually faster: It is designed to automatically overclock itself to 4.1GHz (Turbo Boost) if needed and has 50% more CPU cores for even better multi-core performance. Not only is there no speed issue, I'd describe it as complete overkill for basic email/internet use. Of course if you want overkill maybe upgrade to 16GB Ram as well. The 4K models do not have user replaceable memory and in 5+ years the extra memory might be useful.

If you stay with an external SSD pick any brand you trust. Mac's aren't that picky on storage.

If performance is more important than price then the OWX-Envoy-Pro is a solid crazy fast pick. It's twice as fast as a budget option, but then again thats the difference between being 20-200x faster than your HDD vs only 10-100x faster.

For budget pick drop any 2.5" SATA SSD (I'm a satisfied Crucial customer so I'll suggest the BX500) into a USB 3.0 or 3.1 enclosure. The OWC Express should work as one example. Or as 3rd choice get any portable USB 3.0 or 3.1 SSD from a reputable brand that doesn't have its own hardware encryption: SanDisk, Seagate, etc.

https://www.crucial.com/catalog/ssd/bx500

https://eshop.macsales.com/item/OWC/ES2.5**3B/

Yes, but internal installation is moderately difficult. Since USB 3.1 is fast enough these days to keep up with SSD speeds I generally view internal upgrades as a needless risk.

👍

You still have parts of CMM installed...

/Library/LaunchDaemons/com.macpaw.CleanMyMac4.Agent.plist

Executable: /Library/PrivilegedHelperTools/com.macpaw.CleanMyMac4.Agent

On UCB-C SSDs...

https://eshop.macsales.com/shop/external-drives/OWC-Envoy-Pro