There's a lot of proof that the great works of art of human history involved drug (ab) use for at least eighty percent. (Found cannabis seeds in Shakespeare's pipe)
I guess cannabis lifts you out of a wider view, and makes you zoom in on what you are doing specifically. It may indeed 'enhance' performance.
Plz check out the Pharmacratic Inquisition if you have the time. It's three hours of presentation that 'll blow your mind.

http://www.pharmacratic-inquisition..../pharmacratic/

(!! really)