I've been groping around the idea of Willoughby as a performer starring in his personal drama for quite a while now, and your post makes perfect sense to me.

I think that some aspects of his 'performance' were quite conscious and deliberate, such as his seduction of Eliza and early interactions with Marianne. I see the 'performer' aspect of his character as going deeper than this though, and suspect that a good deal of it is not conscious at all - that he is not even aware that he is doing it.

This ties in with another idea about Willoughby's character which I'm having trouble expressing coherently, namely the feeling that he is a hollow character, that there's an emptiness at the core of him. This inner emptiness could explain a lot:-

-His desire for heightened and intense experience.

-His fixation on material possessions even when he is deep in debt.

-His need for repeated fixes of admiration, particularly from women. When he gets it though, it is never enough, and he may even come to despise those who give it to him, perhaps because of some inner belief in his essential worthlessness.

Taking it further, I wonder if the real 'inner Willoughby' is needy, weak and frightened, though I'm sure he would strenuously avoid having to recognise this. Maybe there's a connection here with his narcissism?