Site Editor Extremely Resource Hungry

This problem may be a plugin or theme conflict. Please attempt to deactivate all plugins and switch to the default Twenty Twenty-One theme. If the problem goes away, re-activate them one by one to identify the source of the problem.

If you can install plugins, install Health Check. On the troubleshooting tab, you can click the button to deactivate all plugins and change the theme for you while you’re still logged in without affecting normal visitors to your site.

I’m not sure how fruitful that will be. Turns out the issue is browser-specific. Something in the latest core update doesn’t play nicely with Firefox, but all is working fine in Safari. Unfortunately, Firefox is my default (and preferred) browser…

I haven’t been having any issues with WordPress 6.2.2’s editor and Firefox 113.0.2 myself.

Would you please try the steps mentioned earlier to rule-out a function conflict introduced by a plugin or theme?

OK, cool. No issues in Firefox with Troubleshooting Mode active…

Ok, in Troubleshooting Mode, reactivate each plugin one by one until you find the one causing the problem.

If it’s not a plugin, then it’s your theme.

Looks like the issue is Jetpack! Very frustrating; I’ve now lost the use of the Jetpack ‘Tiled Gallery’ block, which I really liked (and which I spent ages on trying to get captions to appear on hover using CSS!).

I have reactivated Jetpack but switched off all the settings except the ones I’d need to have use of the Tiled Gallery block. The Site Editor page is still not freezing up any more, so that looks like we have fixed the issue. (I’m still not getting captions on hover with the Tiled Gallery plugin though, even though my CSS remains…)

Ok, please contact Jetpack’s support about this via https://jetpack.com/contact-support/?rel=support if you have a paid plan, or https://www.ads-software.com/support/plugin/jetpack/ if you do not.