I'm pretty sure it's at least significantly due to my stuttering. Although perhaps less so in how often I speak, but in what I say when I do. When writing I feel like I 'speak' much more freely, using more colourful and exciting words and phrases. I take detours to inject a little humour or set the scene, or whatever. But when I'm actually speaking, I get to the point and nothing but the point. If it doesn't *need* to be said, chances are I won't say it.