I've been knitting for a year and a half (although I first learned how many years ago), and I'm a VERY slow knitter. Part of my problem is that I'm easily distracted, so I sometimes tend to put my work down and wander off.
But even when that doesn't happen -- I can very happily spend an entire day watching movies on TV and knitting -- it still takes me a long time to finish anything, and I think I've figured out why. I'm more of a process than a product knitter, and I get a tremendous amount of enjoyment out of the very act of knitting! If I try to make myself knit faster I don't enjoy it as much, it starts feeling like work instead of fun. I might speed up for a few minutes, but then I lapse back into my normal snail's pace.
So I guess I'm just going to have to accept the fact it's going to take me a long time to finish my projects!