iOS 4.2.1 vs. iOS 4.3 – New Nitro JavaScript Engine Shows up to Three Times Performance Improvement

Late last week, the folks over at CNET published an early JavaScript benchmark test performed on iPad 2s, right after the iPad 2 announcement keynote that took place at the Yerba Buena Center for the Arts in San Francisco last Wednesday. While the test showed that the iPad 2 running iOS 4.3 was incredibly faster than its predecessor running iOS 4.2.1, the test was not focused on the improvements brought by iOS 4.3 alone. While we’re eagerly waiting for the iPad 2 to be released on Friday, we decided to run our own series of JavaScript tests, to see if iOS 4.3 – and especially its new Nitro JavaScript engine – would give a ‘second life’ to our aging first generation iPads, and iPhone 4s. Needless to say, the performance of Mobile Safari on iOS 4.3 is nothing short of impressive. Hardware
  • First generation iPad, restored to iOS 4.2.1 (build 8C154)
  • First generation iPad, restored to iOS 4.3 (build 8F190)
  • iPhone 4, restored to iOS 4.2.1 (build 8C154)
  • iPhone 4, restored to iOS 4.3 (build 8F190)
Tests The tests offer a good balance between different areas of the JavaScript language and different types of code. Each test was run 10 times. Results Depending on the test, our first generation iPad and iPhone 4 running iOS 4.3 showed a JavaScript performance improvement of up to three times the performance obtained on the same device running iOS 4.2.1.

As for real-life test results, iPhone 4 and iPad users will instantly notice major improvements on JavaScript-heavy websites, once their devices are upgraded to iOS 4.3. As an example, the JavaScript-based slideshow effect located on top of the iOSnoops homepage looks jittery on iOS 4.2.1, while the transitions between the various pictures look (almost) perfect with iOS 4.3. Back in 2010, the performance of the JavaScript engine in Google’s Android 2.2 running on devices such as the Nexus One made iOS 4 look sluggish at best. Apple got the message, and it shows.