Slow iMac 2017 21.5" Monterey

i've noticed the mac has something norton installed. you should uninstall that as well.

however, i think your main issue is hardware, not installed software. the mac has very slow mechanical HDD. (5400 RPM) it would struggle on catalina, and be pretty much unusable on monterey. that is the slowest drive that was available when built. i think your best bet would be to load monterey onto an external SSD, and run the mac from that. please see this informative user tip: How to Setup and Use an External SSD as your Startup Disk - User Tip.

I can share my experience with my wife's 2016 iMac, also purchased with a 5400 rpm rotational drive. I upgraded it up to Monterey and it was similarly slow like yours. (But I have no Clean My Mac nor anti-virus type of software installed.)

We purchased a 1 TB SSD (Samsung - 870 EVO 1TB SATA 2.5" Internal Solid State Drive) for about $100 and had an Apple Authorized Service Provider independent shop install it as a new internal drive, to replace the original HDD. It is now extremely nimble and lively, boots in seconds, and opens software like MS-Office very quickly. It's like a new computer. I preferred this to use of an external disk to boot. Not only for more speed, but also for better compatibility in the future as Apple moves to more advanced MacOS. Apple has been making it harder to boot from externals in recent years and the trend may continue.

Besides the recommendations of others here,:

Software Installs (past 60 days):

Install Date Name (Version)

2022-04-17 CleanMyMac-MAS (4.10.4)

Uninstall CleanMyMac using the manufacturer's instructions.

Also, you only have 8GB memory. which is really not enough. You can replace the internal HDD and replace the 2 4GB memory sticks with larger sticks if you are p to it. For how see

https://www.ifixit.com/Guide/iMac+Intel+21.5-Inch+Retina+4K+Display+(2017)+RAM+and+SATA+Hard+Drive+Upgrade/92904

Do a time machine backup, go into internet recovery open disk utility and erase the drive; reinstall macOS Monterey and you can restore from time machine at the point. You'll notice a major performance increase....

Very much agree with @jefferythefrog on all points outlined ( early bird gets the worm 👍 )

Antivirus software: Apple and Symantec and the 5400 RPM Rotational Drive.

Any Third Party Applications that will interfere with the normal operation of the OS, alter, modify, remove or delete or attempt to do so is an invitation for disaster and comprising the Operating System

It may require a Reinstallation of the OS in-order to replace any modified, altered, removed or corrupted elements of the OS this software has inflicted on this computer

Any of the below should be removed as per Developers Instructions 

This will included Norton Antivirus , and please please take a moment to read some of the many posing on this specific Application

There are no known Windows-like Viruses in the wild that self replicate and affect macOS, because of the underling UNIX  Foundation and Permission Limitation. 

The Only thing this Antivirus software is protecting is the Bank Account of the Developers and for zero return to the User aside from the problems this software creates.

The The Built in Security  is all that is required.

Follow on previous posting regarding CleanMyMac

Any Third Party Applications that will interfere with the normal operation of the OS, alter, modify, remove or delete or attempt to do so is an invitation for disaster and comprising the Operating System

It may require a Reinstallation of the OS in-order to replace any modified, altered, removed or corrupted elements of the OS this software has inflicted on this computer 

Any of the below should be removed as per Developers Instructions 

This will include CleanMyMac and this is the King of Kings for mucking up the Operating System to point a ReInstallation maybe required to put things right again.

Etrecheck Report is missing. This only thing appearing is below. Refer to image below to get the Full Report posted

" I have a friend's 2017 iMac 21.5" which was running very slowly on Catalina 15.7. Have followed all of the steps recommended in other posts including upgrade to Monterey.

Thus far have deleted CleanMyMac & some other surplus apps, cleaned up Login items, run Disk First Aid, turned off FileVault (for now at least), opened in Safe Mode with no change, did SMC reset, reset NVRAM, tried Safe mode again all to no avail.

Have also created a new user account but no real improvement in login speed.

There are 5 user accounts - 3 admin & 2 standard. I only have the password for one of the admins plus the new one I set up.

Shutdown from an empty screen (no apps running) just took around 30 seconds.

Power up to login screen 1min 30s

Login main admin user 1min 45s (no windows or apps opening)

Open Finder window 30 seconds

Open Numbers (no file) 36 seconds

Open Excel (no file) 2min 40s

I'm aware this model has a slow HDD but these times seem a bit extreme.

I am thinking of wiping the HDD and starting again - maybe just restoring one user at a time or something. However, I guess it might just be the hardware.

Anyway, hoping there might be a solution out there.

Good catch 👍