When I was about 20 I asked my mum, whether musicians take drugs to make them play better. Her reply: You'll probably make more mistakes (playing live) but you wouldnt worry about it so much
pretty cool really. I did perform at a gig totally drunk once, which was a nightmare...dont do that!
DJing is a different ball game and I know the right amount of weed can help you STAY in the groove, but is unlikely to assist you to GET INTO the groove, if you know what I mean.
However, one can use the experience to help you with inspiration /composing in some form or another...not live performance though.
For the record I dont advocate taking drugs. I think it depends on the individual- for some people it is ok to do the occasional E. But never never take such drugs regularly Ive seen a few too many lives screwed up on them.