This begins to happen when there are 15 or more slides. There is nothing notable about the presentation (about 3mb). Selecting a new font can take 30 seconds! The application feels like it's going to crash.
Reboot your Mac. Update to Keynote v12.2 and see if that current version makes a difference.
What else is running on your Mac that is drawing down your performance. Have you installed any anti-virus, or so-called Mac Cleaner product with the notoriety of interfering with operating system functionality and performance?
Greetings myshkin24601,
If an app on your Mac is not working as expected, these steps can help as they relate to issues with apps not working as expected (including Keynote):
If an app on your Mac stops responding, closes unexpectedly, or won’t open - Apple Support
1. Quit and reopen the app
Quit the app, then open it again. If the app won't quit, force the app to quit. Then check to see if the problem with the app is fixed.
2. Restart your Mac
Restart your Mac. Then check to see if the problem with the app is fixed.
3. Check for updates
To see if updates are available for the app, open the App Store, then click Updates. If updates aren't available for the app, update the software on your Mac. Or if you didn't get the app from the App Store, look for updates to the app on the app developer's website. Then check to see if the problem with the app is fixed.
4. Reinstall the app
Delete the app. When you do this, you might lose data that was stored in the app. Then redownload the app. If you didn't get the app from the App Store, redownload the app on the app developer's website. Then check to see if the problem with the app is fixed.
Take care.
On Keynote 12.1 (on Ventura on an M1 max) selecting new/changing the font is very slow
