Back in March Apple updated Mobile Safari with improvements to its Nitro engine, allowing for increased performance. Around this time in April, Microsoft’s demo of their Phone 7 Mango demo was pitted against an iPhone (pre-Nitro) and Android browser in Microsoft’s own HTML5 speed test. 9to5Mac points out Mobile Safari scored 2 FPS versus Microsoft’s 26 FPS, but also the iPhone was rendering more pixels with its 640×960 Retina Display, causing it to lose badly. Here’s the video via winrumors:

Fast forward to Mobile Safari in iOS 5, which now appears to be supercharged because its HTML5 scores in that same Microsoft-designed test are now even better than IE 9 Mobile. Mobile Safari in iOS 5 can achieve frames per second scores of 31.

Here’s a video showing the performance of Mobile Safari in iOS 5 versus iOS 4.3:

Apple definitely added a HTML5 performance boost in Mobile Safari in iOS 5. You can try the test out yourself here. What score did you get?