I've been having the same problems recently, my screenshots would be exactly like Bluntness' above. I'm on an iPad Air2, latest version of iOS 10, on Safari. In particular, Threads I'm On or active convos would load, or partly load, but the little loading wheel would still be going round. If I clicked on a thread title, the blue loading bar under the address box would move about a cm or so, then nothing. I tried waiting for the wheel to stop spinning, but it would take so long I'd have to give up.
I then noticed that when the first page loaded (TIO or AC), the ads at the top and on the right side didn't, and wondered if it might be due to a problem with that.
So I've now done what I always said I wouldn't, and installed AdBlocker on my iPad.
And bingo! Back to normal. I'm sorry about it, because I know Mumsnet needs ads to survive, but if I can't use the site, then I wouldn't be seeing the ads anyway.