being a composer myself, i can tell you that while composition is hard - really hard - performing is more so because as a composer, you have an eraser.
as for research, as a vocalist i never perform a piece before i learn what it's about, and what the composer was into when he wrote it. as a saxophonist, it's the same way. i recently did a piece called Tableaux de Provence on my senior recital. had i not researched it, i wouldn't have known that it was a tribute of sorts to Maurice's time in Provence, France, or that the name (in a slightly obscure dialect of french) means Pictures of Provence, or that each movement was inspired by a unique experience that she had there. THAT makes for a much different performance. just being able to play a piece isn't enough - you've gotta be able to go back and say, 'this is why i did this, and this'.
and by the way, most performers don't have teachers to tell them what to do where on a piece. i haven't had a teacher actually tell me what to do somewhere on a piece in months and months and months. i do my own research, my own listening, and my own studying of the piece.
that's all i'm going to say regarding this argument. if anyone wants to start a thread, that's fine - just link me there. but i'm not going to continue to post.