Comment 43 for bug 1434581

Hm, interesting. When booting with 3.11 from Saucy, scrolling seems quicker (my interactivity local is buggered by a keyboard monitor switch which some day I should replace), at least I could not really read what scrolled by while I could with 3.13. And looking at /proc/mtrr I found a write-combining range added which was not done with 3.11:

reg03: base=0x0fc000000 ( 4032MB), size= 8MB, count=1: write-combining

Cannot say why right now but that could well explain the slowdown.