InDesign 2025 very slow saving documents

I am having an issue with the latest version of InDesign (currently running 20.0.1) where hitting 'save' results in anywhere between 5-15 seconds of spinning beachball of death. I've tried with and without font management software, tried on a clean Mac user account, completely uninstalled and reinstalled InDesign, but nothing works. I also tried saving as IDML but to no avail. I am saving to my iMac HD, not the cloud, although it is no better if I do save to the cloud.

A new document with nothing in it saves instantly, and adding images and non-text items has no impact. I imported a large chunk of 'Lorem Ipsum' text in the Minion Pro regular font, and that also had no effect, but as soon as I start adding different font styles and weights, let alone other fonts, saving gets really slow.

For example, just changing three words to Minion Pro Semibold Subhead means the document takes a full second to save (with a brief flash of the spinning ball), and once I have added 4 other versions of Minion Pro to a few words, it takes a full 5-6 seconds to save. Existing documents with a full set of styled text over 30 pages take 10-15 seconds to save.

The previous version of InDesign works fine with the same documents, so I may have to switch back; either that or break the habit of hitting save quite so often!