When you use Force Speed, your Force power meter immediately drops to half. It will not begin to recharge until the effect wears off, and if you use any other powers while Speeding, it will drop further still.
At level 1, you will move 33% faster than normal. At level 2, twice as fast; and at level 3, four times faster. If your Force meter is at least half full and someone fires a disruptor rifle at you, you may be able to automatically dodge the shot. If not, you'll get disintegrated.