"he talks fast" is perfectly proper English. That's how English speakers speak English. It might not be "proper" academic English, but that represents only a small subset of all the different types of English there are, and just like you will look foolish if you speak non-academic English in an academic setting, you will look equally foolish and awkward if you speak "proper" academic English in a non-academic setting. In that setting, academic English is not proper at all and people will look at you weird (not weirdly, weird) if you speak like that.
oyttb, this is definitely not meant as an insult, but are you from the USA, because in European English "he talks fast" would be considered awful English, and a person saying it would be considered by most, to be very uneducated? However, I do believe that for those using American English it would be considered ok.