Every time I open a pdf or image file using Preview when Preview was not already open, Preview will freeze up for a few seconds. If Preview was already open, i.e. I already had a pdf open and opened another one, then there is no issue with opening the second pdf. I've tried resetting Preview by deleting its files in ~/Library, but the problem still persists.
As a troubleshooting step I would boot your Mac into Safe Mode.
Boot into Safe Mode
Follow these steps to boot your Mac into Safe Mode:
- Fully shut down your Mac
- Restart your Mac
- Immediately press the Shift key and keep it down
- Let go of the Shift key when you see the login window (NOTE: If you have FileVault enabled you may need to log in twice).
- Take a note of what happens (i.e. use Preview a couple of times or so to test it)
- Exit Safe Mode by restarting your Mac as normal
- Log in and test Preview again
Let me know how you go.