My laptop has been running slowly for months. I thought I had problems with the CPU temperature, the CPU itself, spywarre, viruses, global warming, little green men - you name it.
The penny finally dropped. (D'OH!)
My power management settings were set to "Default Power Scheme". So Windows was throttling the CPU to reduce power usage and extend the life of my battery. That's useless to me because my computer is rarely un-plugged.
I changed it to "Minimal Power Management" and WHOOOOSH!!!!! It's running as fast as it used to.
Nice to have decent laptop power again. I've been putting up with crawling speeds for months. If only I'd found this solution earlier!