How to reduce number of screens on HTC Sense android phones?

I was wondering, is there a way to reduce the number of screens available with HTC sense phones to say 5? Just I find that 7 screens is excessive for my needs, and I heard I can get a decent performance / battery boost from having less screens. So is there a way to reduce the number of screens without using a custom launcher (which I think gets rid of HTC sense?) Currently I just have my two side screens blank, but that looks off when you zoom out, however I have found that even that has produced a noticeable improvement on my Desire HD Thanks!