How slow?
Try SpeedTest to measure it (make sure that you are on mobile data and not wifi):
http://www.speedtest.net/mobile/
Was it always the same or has it changed recently?
Is the same wherever you go?
Where are you normally located?
What symbol do you see on the signal bars if applicable - e.g. 3G/G, H, H+ etc.
If you are on Android what does System settings > About phone > Status > Mobile network type say?
What are your internet/APN settings?
If necessary contact 48 support for assistance:
How to get help
Hope this helps.
