I've noticed that if WiFi isn't available, your internet pages will load faster if you turn it off
Remember to turn it back on when you're back in a WiFi area, as it does have it's advantages when it's able to connect to a WiFi
I turn it off anyway in that case to save battery.
sometimes, youtube videos will only load for me over evdo and not wifi. Might just be an old router tho.
podcasts download twice as fast over wifi