Sonomo and Finder/Text Edit

Restart in Safe Mode. Do Finder and TextEdit work there? If they, as I expect, then it means that something that had there already is causing havoc in Sonoma. In that case, Please run Etrecheck and post its full report here. Use the "additional text" button and paste the report into the text box. By looking at the report we may get an idea of what the cause is.

Short answer - a Fusion Drive

They were good to cheap Extra Storage but will never perform as well as an All SSD Configuration

The main stumbling point for performance will be the Rotational / Spinner 5400 RPM Mechanical Drive

Use an external SSD as your startup disk … - Apple Community

Drives:

disk0 - APPLE SSD SM0032L 28.00 GB (Solid State - TRIM: Yes)

disk1 - APPLE HDD HTS541010A9E632 1.00 TB (Mechanical - 5400 RPM)

I also suspect that the Fusion Drive may be part of the problem. It is slow, has only a minimal 28GB SSD part, and could well be failing.

If you have that possibility, running from an external SSD could provide you with much better responsiveness.

In the old days, I'd be recommending this wholeheartedly, but now I have to throw some caution. Apple has been making booting from external drives more and more limited. I think it is still possible, but you will first have to go into recovery, run Startup Security Utility, and actually allow external booting. I worry if this may be further restricted in the future.

Install EtreCheck and post the report. Allow Full Disk Access.

https://etrecheck.com/

Use the Additional Text icon to paste in the report.

May reveal what's wrong with your Mac.