What is needed to browse through PDF's lightning fast?!

I've had this frustration for a while now. I often scroll through large PDF's (24"x36" size), or 8"x11" that are involved in imagery. How is it an i5 Haswell processor will struggle with it. Ok, let me say this differently. How is it I can buy a tough, recently launched ultrabook, with an i5 haswell or better, and still put up with lagging when scrolling through these PDF's? Are there tweaks that I should be doing to my system, which runs Windows 8.1, or what? My i7 quad processor desktop does a much better job, but honestly I'm not impressed either.