SAFE MODE
If you haven't rebooted into safe mode anytime recently you should try that to see if it helps. Let macOS do drive directory repair, cache clearing and other misc housekeeping. When you've started in safe mode the computer may not perform well, especially graphics, because the OS has only loaded the most basic of device drivers. Boot into safe mode with all your external peripherals disconnected but the keyboard and mouse.
Once booted in safe mode, login to your user account and see if the problem persists.
Booting into Safe Mode…
Use safe mode to isolate issues - Apple Support
To boot in Safe mode, restart your Mac and immediately press and hold the <shift> key until you see the Apple logo and progress bar.
Note– starting up in Safe mode could take 10 minutes or more. Be patient.
Does the problem persist while in Safe mode?
Restart your Macintosh and re-evaluate the issue.