Had problems with my system recently and had to revert back to an earlier copy.
Pretty sure this was down to a virus.
Looks like the virus had been there for a while in several copies before it got bad enough fo me to notice.
Anyway, I had to revert to a copy I was using before I had read this guide.
Believe me the drop in speed was very noticable.
I have now installed them again and am much happier with the speed.
I am using a Blizzard 1260 so unless the Shark comes along :-D
I won't be able to upgrade to a better CPU any time soon.
So for all the doubters, I would say give it a try.
Make a backup 1st and you can always revert back if not happy.