All I can offer is from personal experience. Used to do it. Quit some time ago.

In retrospect I realize I had developed a big case of what I think the mental health folks call "state-conditioned learning". The premise is that if you learn how to do something in an altered state of consciousness, you don't do it as well in a normal state. The only time I wanted to play music was when I was stoned. When I was stoned, the only thing I wanted to do was play music. I could play straight, it just wasn't any fun. If I listen to old tapes of my stoned self playing, I hear a very idiosyncratic style that was not really well adapted to playing in a band. Pot made me listen to what was coming out of my instrument instead of the other band members. Several folks remarked on how much more solid my playing was after I quit smoking.

I still have lots of friends that smoke, and I don't have any problem with it. They do it for their reasons - I quit for mine.

Bruce