by surface I suppose you mean texture? well yes each block needs its own texture, even if it's drawing from the same texture that'll course drag too.
I don't mean to sound like I'm talking down to you or anything by the following, so don't take offence.
if you noticed and pay attention to games, you'll notice physics is only used where absolutely nessary, if they can get away with rendering/animating say 10 verations of something in a file they'll do that over trying to use physics for it, becoming slightly less so today, because machines are becoming much faster, but we under basic must be extra vigalent in what we do in regards to physics, because of the over head of our language.
I don't mean to sound like I'm talking down to you or anything by the following, so don't take offence.
if you noticed and pay attention to games, you'll notice physics is only used where absolutely nessary, if they can get away with rendering/animating say 10 verations of something in a file they'll do that over trying to use physics for it, becoming slightly less so today, because machines are becoming much faster, but we under basic must be extra vigalent in what we do in regards to physics, because of the over head of our language.