As a performer the most important critic of your work should be you.
There must be a balance between the inner voices that tell you,
"Look at me, I'm a performing genius", and,"Look at me, I'm a talentless dunce who should have stayed home."
You should have a good idea of what a professional level performance is and be able to measure yourself against that standard. You may fall short, but it will give you a good idea of what to aim towards.
The helpful criticism of your peer performers can be very useful, as you are all struggling towards the same goal.
Helpful critique from your audience can also be a good guide In all of these cases the standard should not be whether the comments are negative, but whether they are true.
An old teacher of mine once gave me great advice I didn't appreciate till years later. "Just because you worked long and hard on something doesn't necessarily mean that it's good." On the other hand, this advice came from a man who had lost 4 spitfires in the channel during the battle of Britain...none of them in combat.
What I learned from this is to take my teachers advice about writing, but not about how to pilot a fighter plane. Consider the source of criticism along with their strengths and weaknesses.                     
Northerner, I must say that I'm quite fond of Jack Campin's idea of performing a story about a critic of all things. I think it's simply brilliant.
Of course, this assumes that the fellow's criticism is offbase.
If this fellow's purpose is to really help you, then heed his words. If he's just getting off chatting to hear himself AND his comments are wrong, then blow him off.