Just to provide an explanation for others in case they stumble across this thread, it was image compression and Migrate 2 that was causing it, two CloudFlare features that work perfectly on PC, but not so good on mobiles.
Also just want to say a big thanks to the XenForo Staff Team. I don't understand how you guys do it, tickets, support threads, threads in general, I see you guys flying around everywhere and you've probably still got a life off here. You guys must have good commitment, because personally I'm not sure I could do that. One thing is for sure, you guys definitely have the best support and community here than any other forum software I've used or seen. Quality, timely. And of course all of these addons and wide range of work that takes time to maintain. Thank you.