Easiest/quickest way to break up with someone?

What's the easiest, quickest way to break up with someone without being rude or seeming like an ? I don't think my gf is horrible or anyhing, I just don't think we have very much chemistry, but I'm finding I have the same locked up feelings when I try to break up with her that I usually do for asking people out. I have a feeling that breaking up by text wouldn't be prudent but I'm not sure how to do it easy any other way.