My Imac has become slow.

You have installed the malware CleanMyMac on your computer. Mac OS is the best antivirus and cleaning app for Mac OS, in order to Mac OS secure simply keep it up-to-date and otherwise leave it alone. Mac OS does not benefit from nor does it require any third party "maintenance" apps including antivirus, cleaning, security, or anything else. If you want Mac OS to be slow, unstable and appear buggy then please keep CMM installed. Please locate the developers uninstall instructions and follow them. Then please restart the computer in Safe Mode per Use safe mode to isolate issues with your Mac and then restart normally.

Finally, it's okay to keep your iMac running, however your report show it has been running 18 days so the Safe Mode restart will help that. It may be good practice to keep it running about a week and then just restart it.

Finally, this is a base model iMac with only 8GB of RAM and a glacially slow 5400 RPM HD. There is nothin you can do about the RAM, however if you want you can get an external SSD like ( https://eshop.macsales.com/item/OWC/ME6CM6EPT01/ or https://eshop.macsales.com/item/OWC/ME6UM6PGT1.0/) and then use a cloning app such as SuperDuper! or Carbon Copy Cloner to clone the internal HD to the SSD. After the cloning is completed, boot from the SSD and set it as your startup drive. Finally format the internal HD and use it for additional storage. You will be shocked at the improvement in performance.

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click https://discussions.apple.com/docs/DOC-250000211

I'd uninstall CleanMyMac to start with according to their directions, then see if we can improve this problem...

Virtual Memory Information:

Physical RAM: 8 GB

Free RAM: 23 MB

Used RAM: 4.97 GB

Cached files: 3.01 GB

Well the report looks okay, however as I stated earlier you have a base model iMac and it will never be fast. The model you purchased is designed for doing e-mail and some modest web surfing. Other than that it's pretty much reach what it can do efficiently. It has 8GB of un upgradeable RAM and the last report shows only 16 mb are free and it has a glacially slow 5400 RPM HD.

You cannot do a thing about the RAM if you want to keep it, however you can get an external SSD and that should help quite a bit. You can clone your HD to the SSD and then use the SSD as your startup drive and then use the internal HD as overflow storage. Other than that you simply bought the wrong configuration for your needs. Users that buy 21.5" iMacs should get a bare minimum of 16GB of RAM and the largest SSD they can possibly afford.

Download FindAnyFile and have it search the drive for the words CleanMyMac and MacPaw

As mentioned...

Find Any File...

http://apps.tempel.org/FindAnyFile/index.php

Hold Option or alt key when selecting Find to Find All.

Please post a new EtreCheck report and we can look again.

Well, I suspect some hardware issue because nothing showing to make it that slow, Available RAM: 3.31 GB, so it's not paging in.out to the HDD.