iPhone 3G and iOS 4: Benchmarking the 4.2 Update


I’ve seen the videos online of iOS 4.2 running smoothly on an iPhone 3G. Most of these reviews have proclaimed that iOS 4.2 is faster than iOS 4.1.  The following benchmarking results challenge this perception. I ran the update through its paces on my 3G, and this is what I found.

iOS 4.2.1 Update Tested

To test how iOS 4.2 affected performance, I took an iPhone 3G and ran it through the same series of performance tests I did when iOS 4.1 was released. Just like last time, I used GeekBench 2 ($1.99), Gauge Mathematical Tool ($1.99), BenchTest (99 cents), SunSpider (free) and V8 (free) to test the performance of each OS version on the 3G.

Also like last time, the 3G I was testing was still running with a lot of features disabled, and was being used more as an iPod touch than as an iPhone. I am reusing the same data collected last time for comparison. The following results are only a subset of the data collected, and focus on the data points that changed the most from version to version:

Results for iPhone 3G: The 4.2.1 Update

While some things seem to have improved slightly, like JavaScript and drawing new content when you switch views in an app, other tests have dropped off considerably. Memory performance as measured by GeekBench, as well as the executions of Gague’s Prime Number test are especially bad. These would affect apps that are doing much more than just displaying or editing a simple screen, like an RSS reader, for instance.  It would have a greater impact on apps performing more advanced computational functions, such as Documents to Go.

Just informally trying out several core apps like Apple’s Notes, Safari, Calendar and Contacts revealed more than the benchmarking tests indicate, however. Scrolling speed and data entry appear to be much improved. It seemed as though my performance tests were contradicting my real world experience.

One More iPhone 4 Test: The 4.2.1 Update

Testing on the iPhone 4 was the best way to find out if the performance degradation I was seeing on the iPhone 3G in the tests was really something to worry about. I reused the same benchmarking data collected in earlier tests for comparison. I was looking for the same degradation in performance in the same areas.

Since both the GeekBench Stdlib Allocate test as well as the Gague Prime Number test degrade on the iPhone 4 as they did on the iPhone 3G, I had to conclude that it was an issue with how the test was seeing changes made to the iOS firmware in version 4.2.1, and not necessarily a reflection of actual device performance.


While data entry, scrolling, pinching and zooming have improved slightly, the 3G is still not up to par with its newer siblings. Where we see the most gains on both the iPhone 3G and the iPhone 4 is in the JavaScript results.  Whatever the Webkit/Safari team is doing, it is having a positive effect with each release.

Bottom line: If you’re still using iOS 3.1.3 and use sophisticated apps that are heavily computational, then it’s probably best to avoid 4.2 (that’s easier if the apps you’re using don’t require 4.0 or higher). If you’re content with the apps Apple provides and mobile Safari, you should be fine. If you need the more demanding apps, and those apps need iOS 4.0 or higher, it might be time to consider that hardware upgrade.

Online Benchmark Results

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