I reckon the fastest bolt actions must be those used on the straight-pull 5-shot Biathlon rifles, such as those made by Anschutz. However, I am not aware that they come any bigger than .22 rimfire...

Other than that, I also reckon that the Enfield is tough to beat on speed and reliability. I don't own a Blaser, but have shot them - my impression is that the bolt has to be cycled relatively far to the rear. Combined with the angle of the bolt handle, I reckon this might actually cause cycling the bolt to be slower than it would at first appear, although alot is down to practice I suppose.