If I change the network form Global to 1XEV, will the internet be slower?
no it does not decrease speed...
it actually improves battery live
what global does is allows the device to jump onto a network besides for CDMA..
if you leave the US you will need this mode..
but in the US your device will never jump onto a GSM network unless you unlock it and put a sim card into it for another network such as AT&T while on at&t you would only receive a edge connection so it would be much slower as its not 3g
the only 3g network you can connect to with the device in the USA is CDMA which will show on your device as 1XEV
there for setting it to a forced 1XEV will not slow the device down and has not for me