As others have said.. there is no "fast lane.." there is just a passing lane. When you're in that lane you should be going faster than the vehicles in the lane to the right of you to complete your pass and then move back over to the travel lane, but you also want to try to keep it within 10 mph of the actual speed limit. As my trooper friend says.. 9 you're fine, 10 you're mine. Most importantly, however, don't weave like a jerk. This isn't a video game. Drive safe out there.