Ok, if you do a binary search on the other plugins and try to pinpoint which one is causing this, then this can guide me in the right direction.
Deactivate half plugins, then see if the offending plugin is in the active ones. If it is, then deactivate half of the active ones and check again. If it’s not, try activating half of the deactivated ones. If you can do this until you determine which one it is, then let me know which plugin is causing the timeouts and I’ll test to see what the problem is. If you have N plugins you will have to do at most base 2 log N tries I think.
It could be some security plugin or caching plugin.
Unfortunately I can’t help in any other way unless you can at least pinpoint the plugin. If you do, I’ll look into the plugin and find the problem.
Good luck, let me know.