It all depends on what you think drifting is, race drifting is the fastest way around a corner but it involves very little sliding. All the "exibition" type drifting with lots of countersteer is slower in almost all cases.
A good show of race drifting would be used on turn 7 right after the corkscrew on Laguna Seca, If you grip that turn, you will almost be ready to shift into 4th gear in a C5R at the end, but if you have a little slide at the beginning of the turn, you have a better chance of extting the turn already in fourth gear.
To achieve fastest possible times you utilize the most grip possible. It's simple physics, grip=acceleration=speed. There'll always be an angle where you can sweep out of the latter half of the turn and hit an apex while under full acceleration.
just experiment with both styles of handling and see what suits you best....although...for my opinion there are SOME hairpins that you can drift faster than you can grip.
