Why is my straight talk iPhone data so slow?

I have a jail broken iPhone 4s which I use with straight talk. When I first got it I downloaded a program on safari and the 4g and mms worked perfectly and I could watch Netflix. But I reset it and and this time I could not find the program I downloaded last time, so I used tetherme and now my Internet is so slow, but it still says I have 4g

Iofhiorehgiorhioiog just wanted my 2 points