Your iPhone CPU doesn't suddenly become an iPhone 3G CPU sometimes, but network availability does vary a lot. You may also one day find yourself on a flaky 3G

Your iPhone CPU doesn't suddenly become an iPhone 3G CPU sometimes, but network availability does vary a lot. You may also one day find yourself on a flaky 3G connection needing access to some web app that first loads twenty megabytes of junk before showing the 1 kB of data you need, and then it's clearer what the problem is here.