In our experience on a Hyper-v Guest running Win Server 08 64 bit the cpu usage grew slowly/steadily over time from page swapping until a reboot. As we added some monitoring software and got busier it grew much quicker. Our baseline usage is fairly low. The baseline would get up to 70%, we would reboot and it would go back to 15%. With lock pages in memory enabled the growth slowed substantially and with a tweek or 2 to better accomodate the monitoring usage, baseline cpu usage stays between 15 and 30%. We have 5 instances of SQL running on the guest with 70-80 (250GB tot) mostly low usage databases. This guest runs on about 30gb of memory mostly allocated to the SQL instances.