An easy thing to do would be to delete the cache folder in the wow folder, it’s just temporary files. Sometimes they can get corrupt and cause issues.
Some add-ons can also cause issues. If add-ons fault they don’t always tell you but handling that fault can slow down your PC. Make sure you have up-to-date add-ons. Check for add-ons that don’t match the current wow version and disable them, if that doesn’t work disable all add-ons and see if it happens.
Do you have other stuff running in the background, maybe overlays like steam or Overwolf etc.
Check the load on your PC. While you have a fairly recent PC you may have put setting up too much. Things like AA and shadows use so much resources for very little benefit. Turn then down a bit.