When home, I cant really play if I am stressed or have things on my mind.  
 
When playing with others, or at a gig, if I am stressed I dont know if I play better, but after a little while I get unstressed and happy.

Good thread!!
 
I agree that there are different kinds / levels / reasons for stress. Sometimes stress triggers more adrenaline and that really helps me stay on top of every note. Others times there's so much stuff running thru your mind that the whole night seems like a blur until you listen back.
 
The last band I was playing with was the first time in a long time where everyone else was competent at troubleshooting their own equipment, so there was a certain level of relaxation & everyone would comment as to how I was yawning thru all 3 sets!