Testing across different devices isn’t always possible so we fallback to using emulators instead. Unfortunately this doesn’t mimic the slower network connection that can sometimes be experienced with mobile devices. This short piece from Alex Fish explains how you can do that in OSX Lion.
Many a time has arisen when simulating a slow 3G/Edge connection is required for testing purposes, which without building to a device with the current required connection is a lot of hard work. This nifty tool can be found in /Applications/Utilities/Network Link Conditioner and will install to your system prefs pane.An excerpt from Simulating connection speeds on OS X Lion