This is an obvious UIWebView issue and Apple knows it. It's been confirmed that these issues exist on most versions of the iPad. Both caching and memory handling issues. There have been plenty of posts confirming this in Apples communities and other developer communities around the net. I've also experienced this extensively in my own testing on all iPads but the Air. Which is only because I haven't gotten my hands on one. I've just been flabbergasted by the negative performance differences between iOS 6 and iOS 7.
The most disturbing example of caching not releasing was when a friend of mine embarrassed themselves at the coffee house. He turned on his ipad, and there was a pornographic image on the screen for a second before it refreshed. When the cute bistro girl could see it. What is even more frightening is that EVERY TIME this happens, it's after another session has been established. This can be reproduced with 100% reliability. After the old cache clears it loads the current cached pages and returns to normal. Why are we seeing cache from the session before the current session? Why doesn't this happen to other applications utilizing the UIWebView API? This is a MASSIVE security issue on so many levels, Apple.
Not only is safari having problems clearing page caches, but system memory is not releasing properly either. Multiple open pages with CSS frames will quickly bring the browser to a grinding halt, where it will crash upon closing it and opening it again... After ANOTHER long hang. This coupled with the other CSS issues can be crippling for websites on iPad. What's worse is that the memory leaks and CSS implementation issues crushing browsing performance are present in all apps that use UIWebView.
This has been a problem ever since iOS7 launched last year. Apple what are you doing to fix this? This isn't a minor issue. It happens several times a day and these posts have been showing up for months about every ipad that supports iOS7. I don't have the time to rebuild a custom version of a website JUST to suck some more performance out of your hastily implemented, poorly tested code. What the heck happened Apple? This is completely out of character for you.