Before trying to shift as fast as possible, check a few things first. One is how old your gearbox is. This is relative because as it gets older your syncros and cones will start to wear out. Those two things alone will slow down shift time. The more stress you put on these parts, the faster they will wear out. Don't try to rush the synchronization process. Instead, try to make the amount of time it takes to synchronize less/faster. Start off with fresh fluid. Next, make sure you do the rev hang fix. The faster your engine drops in rpm's, the less work your syncros will have to do. Lastly, make sure your not on the throttle when you begin to step on the clutch. Being out of sequence here is more common than I realized amongst drivers. You must allow the engine to decelerate on an upshift! There isn't really any shift time to be gained by pulling on the shifter really hard. Just ask anyone who has driven/raced my car.