iMac running slowly

Welcome!

Well, this is a problem:

Performance:

System Load: 1.73 (1 min ago) 1.53 (5 min ago) 1.26 (15 min ago)

Nominal I/O usage: 31.89 MB/s

File system: 29.15 seconds

Write speed: 321 MB/s

Read speed: 845 MB/s

You Apple Fusion drive should be running at minmum twice the speeds it is posting. In that model iMac, a healthy Fusion Drive should be posting Writes of 500-800 MB/sec and Reads at up to 1400MB/sec.

That is not a death notice. There are suspects present that can cause slow drive response.:

1) Use its uninstall tool to completely remove Symantec/Norton. Evidence of its excesses are right there in the diagnostic information:

Diagnostics Information (past 7-30 days):

2023-08-24 08:48:18 SymDaemon High CPU Use (2 times)

Executable: /Library/Application Support/Symantec/*/SymDaemon

2023-08-20 11:08:33 signpost_reporter High CPU Use

Executable: /usr/libexec/signpost_reporter

2023-08-17 14:12:46 com.symantec.mes.systemextension High CPU Use

Executable: /Library/SystemExtensions/*/com.symantec.mes.systemextension

2) Remove the WD and Seagate drive software.

Then we can see if the drive scores improve.

is it time for a new computer?

Too early to say with the Norton bull in a china shop in the way of proper performance evaluation, but this would be a good time to let your Mac be a Mac. Apple builds lots of very effective self-maintenance and defense routines into the OS; third-party stuff sold through fear marketing gets in the way of what you paid Apple to create for macOS.

You have plenty of RAM and, if you can get the disk scores up by dumping what is not needed, I'd say you still have very useful Mac. My 2017 is still going strong.

Dump the dead weight, restart the computer, and run another report. Then we can have a clear view of whether your Fusion drive is up to a few more years of unencumbered service.

It doesn't look too bad for a 21.5" iMac.

macOS has all the built-in security that is necessary.

macOS - Security - Apple

Get rid of the Norton Symantec junk as per the developers instruction.

Then start in Safe Mode followed by a normal Restart and test.

Use safe mode on your Mac - Apple Support

Get rid of the Symantec app. There is no need for AV other than what macOS provides. These type apps are known to disrupt system operations. Use the developers instructions to uninstall the app.