How to increase my website's loading speed


I'm aware there's an insane number of articles on that, but, as some in the WPMU staff know, my site has some "particularities", haha. I'm doing everything I know, I've even purchased the pro version of Wordfence and activated its caching app, but since GoDaddy and SiteLock implemented a bunch of security measures, my site started to have a really slow loading speed. I'll contact them on that, but still, I'd like to know of any tips from you guys.

If necessary, I've sent my credentials with Tyler's name on it like 2 days ago.