IOS – Why is Safari on iOS 10 not rendering some pages correctly

I would imagine this has something to do with Core Data, memory warnings, or both. If Apple is using its own kit, then it is saving the cache in a Core Data store, which is, essentially, an unordered set. My theory is that when you go to a site, Safari is going to the Core Data store and grabbing the first instance of the URL in question if it exists, which can be old, new, whatever. But since I also don't think that Apple would be nearly that sloppy, I'd say that every page attempts to cache, but the amount of data required to properly cache a site is beholden to memory warnings, which you, as the user, should never, ever see, only this time the newer page simply doesn't get cached and that's why you get random older pages in view.

Okay, that was a bit technical. In short, I think Safari attempts to maintain a clean cache, but memory limitations of the device don't always allow that to happen.

Not at this point, no. WebKit, that which Safari for Mac OS and iOS are both based on, is supposed to support WebGL but I have yet to be able to get it work properly on Mac OS 10.6, much less iOS. I get the impression the whole thing is too new (relatively) for proper support.