Hi Jon,
A good check is to look at the browser dev tools network panel. Right Click > Inspect the site in Chrome, open Network tab and then perform an Empty Cache and Hard Reload ( Hold click on Refresh ). You can then see what is loading and when.
Challenge those requests:
For example: Font Awesome – you’re loading 3 x fonts ( + a lot of CSS that is related to them). Could you replace your icons with SVG to remove these additional requests?
Then look a the JS files being loaded – would it be better to Defer loading the 3rd party scripts using a plugin like Flying scripts. This will completely remove any render blocking they generate.
In regards to optimizing the other plugins. I would recommend doing most of your optimization in Autoptimize and just use W3 for page caching – what you want to avoid is having both plugins perform the same functions.
Hi Jason, can you raise a new topic so we can look at your site in isolation.