Preview not responding

Have you tried restarting your Mac?

Mac's go through a 'cleanup' routine on every startup, sweeping out the crud that tends to accumulate.

Have you tried a 'Safe Mode" restart?

Sometimes a 'normal' restart isn't enough. A startup into Safe Mode triggers a more extensive set of clean and repair routines.

It takes longer, and you will observe a distinct slowdown and much worse video performance during safe mode.

To perform a Safe Mode startup:

• In the Apple menu, choose Restart

The computer will go through the regular shutdown routine, then automatically restart.

• Be ready, and press an hold the Shift key as soon as you hear the startup chime.
• Keep the shift key pressed until you see the Apple logo and a progress bar beneath it, then…
• release the key and wait for the startup process to finish.
• Log in.
• Launch Prevue, and load a file (I would AVOID using the 600 page file at this point.
• Other than slowness and degraded video performance, does Preview behave normally?
• Go to the Apple menu and do a normal restart.
• Lunch Preview, and check its performance again.

Further information on Safe Mode here: Use safe mode to isolate issues with your Mac - Apple Support

Regards,

Barry