Strange result on multiple runs with iPhone 4 iOS 5.1 (Dulles, VA)

When doing several test runs at once using the iPhone 4 iOS 5.1 setting from the Dulles location I’m seeing considerably longer load times (for first view) on the first run than on the subsequent runs.


In this test, the first run takes roughly 8 seconds, while the subsequent 7 runs take about 4 seconds or less.

I’ve tried this on a couple of different sites, and all show the same behaviour. However, it doesn’t seem to affect other mobile device settings like the Motorola G or the Nexus 7, which both show consistent load times for first view (see examples below).

Does anybody have a possible explanation for the results from the iPhone test?

The Android devices are using a newer agent technology and I’m a lot more confident in their results. For the iOS agent it’s likely that the OS DNS cache and certificate caches aren’t getting cleared so subsequent SSL negotiations will be faster.