If it really is an engineering challenge it needs to be fixed. We're going on 2 years of Mobile Safari having JIT and UIWebView not having it. They can simply make an exception for UIWebViews without making an exception for the rest of the app. I don't know their codebase and it might be really really hard to fix, but I hope it isn't something they've given up on. It cannot continue in perpetuity, as the web cannot continue to evolve if the makers of one of the most popular browsers have given up on speed improvements.