According to a poster Hacker News, the Nitro JavaScript engine brought to iOS 4.3's Safari browser, is now available to embedded UIWebViews and home screen WebClips in iOS 5. Apple originally claimed the Nitro engine, ported from desktop Safari, would make iOS Safari 2x faster, but due to restrictions on code interpretation (Nitro uses JIT, or Just-in-Time compilation), it was only available in the Safari sandbox. This effectively made web pages embed in apps and saved to the home screen feel twice as slow. No longer, according to this thread:
Q: Did they fix the bug from 4.3 where home screen web apps don't use Nitro?
A: This is probably breaking my NDA to say this, but yes, they did. Web.app now has the "dynamic-codesigning" entitlement, which enables Nitro.
In other words, embed webpages and home screen web apps just became first class citizens, and should have the speed to prove it.
[Hacker News via CNET]
Reader comments
iOS 5 Features: Nitro Javascript engine comes to UIWebView, WebClips
Not in UIWebView according to the same post only in home screen webapps.
Hopefully comes to UIWebView, I want to use a real tabbed browser on the iphone. (Damn you apple for making real tabs for iPad only in ios 5)
i wonder if jailbroken, you can edit the plist to enable tabs. Kind of like how people would enable wallpapers and multitasking to the 3G