Yes, I like responsive too, although it’s borderline industry jargon. I still think snappy is perhaps a bit more down to earth but I don’t know how common it is outside of American English, which could be a problem with an international audience.. words are hard.

I think the important thing to get across isn’t binary size or even RAM usage per se, but rather that it’s the opposite of bloated. Regular non-techies are tortured every day with really slow and unnecessarily networked applications. There was a thread like a month ago about the 400+ MB LinkedIn iPhone app.