Also got CloudFlare on it because we use CDN and dDOS protection via them, and their systems cache a lot. And I've been making a lot of changes. So it might relax. But might be Javascript related.
Takes a while when so many people are involved but I can confirm the forum change has been awesome for traffic and search results and every other metric going. So I'm not stressing too much.
@Bri if you log out on iPhone does it lag on page load then?
Just checked on a couple of other sites, it's only this one that's loading slowly. It's very stuttery, when loading as well, little freezes when scrolling down the pages.