Apple's iOS 5 will close the speed gap between web apps run inside the company's Safari browser and those that run in "fullscreen mode" from the iOS home screen, according to a web post from a developer with early access to the operating system.

With the current version of iOS, web applications saved to the iOS home screen and launched into "fullscreen mode" do not benefit from certain tools built into Safari, including the browser's new Nitro JavaScript engine.

But on Thursday, during a discussion on Hacker News, a developer calling himself Xuzz said that with iOS 5, fullscreen web apps will at least have access to Nitro. "Did they fix the bug from 4.3 where home screen Web apps don't use Nitro?" asked one poster. Xuzz replied: "This is probably breaking my NDA to say this, but yes, they did. Web.app now has the 'dynamic-codesigning' entitlement, which enables Nitro."

But he indicated that Nitro is still missing from the UIWebView API used by native iOS applications, attributing this to Apple's security stance on Nitro's JIT (just-in-time) compiler. "They don't [get Nitro benefits], but that's a security restriction," Xuzz said. "They can't give dynamic-codesigning to all apps, or their security (which that disables, as a requirement to enable the JIT) would then be useless."

It's unclear whether Apple has changed the cache and synchronous mode discrepancies.

With Apple's current operating system, iOS 4.3, the discrepancies between home screen apps and Safari apps creates a significant performance gap. In tests run by The Register, Safari on an iOS 4.3 iPhone 4 run the Sunspider benchmark in about 4047ms. Running from the home screen, it took about 10747ms. It should be noted that users can not run web apps in fullscreen mode unless the developer allows them to.

(Source: theregister.co.uk)