T-Mobile internet dongle slow!

Hi there,

I have a laptop running Windows 7 with a T-Mobile internet dongle (SIM with 6 months web) and it works perfectly.
I have another laptop running Windows 8.1 which is the problem. Using the same dongle it takes ages to get to any page on the internet. I've tried stopping the firewall and updating drivers and programs. I don't know what else to try.

Any help would be gratefully received.