Wider bars make my bike feel faster off the saddle
 

I'm not kidding!! :p Try it.
I went from 42s to 44s (center), and my bike feels a little faster when I ride off the saddle.
And it's not just when I'm really ripping on the bars, but even when I'm just 'leaning' on them when I rock from side to side up a hill.

I figure it's due to the perception that there's a little extra leverage, even though there's more than likely a little more flex :p

I find it to be the other way around. I felt weird when sprinting on 44s compared to 42s.

It's because you have a more stable platform upon which to stabilize your core so they can contribute to pedaling.

^ agree you have a more stable platform and added leverage having a wider bar how ever you can get to wide also, which can also cause shoulder and elbow problems as well same for to narrow of a bar.

I hate narrow bars, and I'm pretty skinny. 44 min.