What does the little circle mean on my Sprint IPhone 5?

For the past few days I've had a little tiny circle in the top left hand corner of my IPhone 5 instead of the 3G. My phones been slow, doesn't connect to the internet and doesn't refresh. It's really bothering me. I've turned the IPhone off & on & that didn't help. I've tried connecting to Wi-Fi, going into my settings to fix it but nothing seems to work.

That means you are using GPRS which is 1G, which will explain the internet speed being slow & sometimes not working.

You could contact Sprint about it since that is on them & their data network.