How can I configure Aquamacs auto-save? Every so many typestrokes Aquamacs tries to auto-save. Unfortunately where it autp-saves is a folder that doesn't exist.

The result is that it freezes for several seconds.

How can I configure it - be it the frequency or turing it off, or the save location?

I've tried to find where but no success.

Can you help please?
The auto-save folder is determined using the variable 'auto-save-file-name-transforms', which you can customize.

The default value of this variable is "~/Library/Caches/Aquamacs Emacs/AutoSave".  The easiest thing to do is to simply create this folder (no customization required).