I would devote some of your practice time to learning rudiments. It has helped me to get faster, and also I'm starting to work them into my fills.
My favorite site for learning them is
Http://www.vicfirth.com/education/rudiments.html
They have videos showing how to do them and MP3 files at different metronome markings to play along with. Start slow when you start to tense up back off on the tempo and relax eventually if you concentrate on not getting tense when you get faster you'll overcome that.