Yes... I nearly always type in proper English instead of quick IM language. I will occasionally use "LOL", especially when talking to my sister. Even when I am on IM with someone, I still type in a similar manner as I do in the forums or via e-mail. It really annoys some people (ie, my sister), but other people do the same thing.
Aside from the "LOL" abbreviation, I also tend to use "M'kay" or "s'ppose", but that is more for dialect than for time efficiency.
_________________
Itaque incipet.
All that glitters is not gold but at least it contains free electrons.