It seems that, as time passses, all applications become more power hungry,
more RAM is used, more disc access [virtual memory paging] makes an SSD a necessity.
However - Just to be sure,
Perhaps try resetting Photoshop preferences again?
Resetting restores Photoshop's internal preferences, which are saved when Photoshop closes. If they become corrupt then various issues can occur.
Here’s some info on how to do that:
https://helpx.adobe.com/photoshop/using/preferences.html
And
https://community.adobe.com/t5/photoshop-ecosystem-discussions/quick-tips-how-to-reset-photoshop-preferences/td-p/12502668
You may want to backup your settings and your custom presets, brushes & actions before restoring Photoshop's preferences.
Here is general info that: https://helpx.adobe.com/photoshop/using/preferences.html#BackupPhotoshoppreferences
Also take a look at the following article and check if that helps:
https://helpx.adobe.com/photoshop/using/printing-color-management-photoshop1.html
Preferences file location: https://helpx.adobe.com/photoshop/kb/preference-file-names-locations-photoshop.html
It may even be time to reinstall Photoshop.
Its recommended that you use the Adobe CC cleaner tool to remove all traces first.
Uninstall Photoshop BUT make sure to choose the option “Yes, remove app preference”.
Once that process finishes, start the installation process and look into the “Advanced Options”. Uncheck “Import previous settings and preferences” and choose to “Remove old versions”.
I hope this helps
neil barstow, colourmanagement net :: adobe forum volunteer
google me "neil barstow colourmanagement" for lots of free articles on colour management