[BD]

Just because you have cable it doesn't mean you're guaranteed to have a ping between 30 and 70. There are other factors involved, such as how busy the server is, the memory (RAM) on the server machine, distance from the server, et cetera.

Pretty much the only way for you to reduce your ping is to shut off any other programs you have running that use the internet in any way. Ignoring that, you could get a new ISP, since a lot of ISPs these days have a throttle in place, meaning your max speed is limited. Some don't, though.