That's my biggest reason for switching from AdBlock+ to Privoxy + https://github.com/skroll/privoxy-adblock . Same blocking rules but uses a ton less memory, since each tab isn't running all of AB+ .
That's fine for image and flash ads, but provides no support for CSS blocking of elements. My understanding is that the CSS blocking is the slowest part, too.
Of course, if you don't want that, you're sweet.