Looking like webfonts is a major time consumer..... would it be worth getting rid of them?
Oh amn then i see that 3 second one you were talking about l**o!! Any way to reduce that speed? Thats massive lol.
If you will test LiteSpeed cache
https://wordpress.org/plugins/litespeed-cache/
keep in mind that you can exclude (and you should) the forums BUT the optimizations (css/js/http2 push) are different and will be still be used in the forums (until you exclude them from optimizations).
So no caching for the forums, while other optimizations will be active.
No problem, ask whatever you want.
I do know what you mean, trying several things on a production site. Not easy.
What you can do is disable for a while Fastest Cache and Autoptimize. And install LiteSpeed cache for caching ONLY. Everything else disabled. And see how it goes.
There will be no change in anything. Replicate the settings from Fastest Cache (like excludes and cache duration).
If you are satisfied and all work well, try to optimize.
For caching all you have to change in the Litespeed is Disable caching for logged users.
The other way is to replicate your site from a backup to a test subdomain and try various settings.
Legend!! Thanks for all your help mate, im going to do all this now, im sure ill be back soon with more questions lol