Lots of respect for replying to a pretty snarky comment and admitting that you were wrong with good humour, if everyone was like this internet comments would be a whole lot better :)
Ah crap, did it come across as snarky? I'm not very good at conveying tone through comments, it was supposed to be mildly poking fun while making a minor nitpick.
Being wrong is fantastic, because it means I have learnt something. In fact I recently had to optimize a troublesome loop and got acceptable results (15 minutes down to 2 minutes thanks to branch mispredicts). Given what I saw today I can go back and see if splitting it up will result in any performance gain.
Which is funny, because your method still uses 2n multiplications, it just computes them in the same loop.