Forever Spinning Beachball - How do I attached the EtreCheck Report

The report suggests that you have a failing hard drive:

Write speed: 42 MB/s

Read speed: 41 MB/s

The first thing you should do is confirm that you have a full and current backup of your internal boot drive.

One course of action you can take is to get an external SSD, clone your boot drive to it and boot and run from it. Your internal HDD is larger than most available SSD (the largest being 4 TB but very, very expensive).

You could get a smaller external SSD, like 1TB, for the system and user data with Music and Photo libraries on another external drive, either SSD or HDD.

What I use is the following SATA to USB drive docks from OWC (MacSales.com) with bare SSDs:

These would be easy to take with you when you upgrade your iMac and used for external storage and beta system testing.

Another possible alternative would be this setup:

Larger bare SSDs are less expensive than those with their own uses.

Just some food for thought.

You have a 2015 model, that's 7 years old. Definitely could be a failing drive. You also have a mechanical (spinning) internal hard drive, those run extremely slowly under Monterey as they have to be in APFS format, which is poorly suited to mechanical drives (APFS is optimized for SSDs).

https://bombich.com/blog/2019/09/12/analysis-apfs-enumeration-performance-on-rotational-hard-drives

Also the report says performance is "poor":

Performance:

System Load: 1.74 (1 min ago) 1.80 (5 min ago) 1.81 (15 min ago)

Nominal I/O usage: 4.66 MB/s

File system: 134.49 seconds (timed out)

Write speed: 42 MB/s

Read speed: 41 MB/s

Those are very slow numbers. I get 500 MB/s on my iMac late 2015 (which has an internal SSD), and 3000 MB/s on my 2019 MacBook Pro (internal SSD). I would expect at least 150 MB/s from a healthy mechanical drive..

I think running the suite of Microsoft, Adobe and Parallels (VM) applications together would make any computer under Monterey and a mechanical APFS drive unacceptably slow, but on top of that yours appears to be failing.

You can check this yourself by downloading and running DriveDX, run the long, extended test, not just the short test.

Assuming that you confirm that the internal drive needs to be replaced, replacing it with an SSD will speed things up by a factor of 10x or more. I don't know who the technician was that tested it for you, but I would have it tested at an Apple Authorized Service Provider. They can also replace the internal drive for you, if that is what needs to be done.

Paste the entire report in using the Additional text button below, it looks like a sheet of paper.