As im doing a render on my 4 year old Dual Athlon MP 2000+ it used to do renders in realtime or pretty close on straight DV... I'm rendering now and its about 2 to 3 times slower.... Can't wait to get my Quad!!!
I've noticed a similar effect in daylight this year. I could swear that we have less daylight today than we had last week, and even less than a month ago.
It seems that daylight is a function of temperature. Ever notice when it gets colder, there is less daylight? I've read on the Internet that the colder temperature causes photon output to decrease. <g>