I've done a fair amount of reading and searching on CPU Usage in Windows 7 (both Beta & RC 1) and haven't had any luck with this issue yet. The machine I'm using contains: Asus P4P800 motherboard Intel P4 2.8 GHz dual core 2.5 GB of ram GeForce 7800 GS 256MB Clean install of Windows 7 RC1 (had same problem in Beta previously) The issue I'm having is my CPU Usage spikes up to 80-100% very often and performance of any other task during this period is frustratingly laggy. These spikes happen from even the simplest action ranging from opening the start menu, to scrolling through text on a webpage and worst of all playing video (Youtube is my benchmark tool, 80% usage guaranteed during video play). Using any web browser with 3+ tabs open is guaranteed to spike CPU usage over 50%. Multitasking in general begets a sluggish OS performance. Some of the solutions I've read and tried: Installing NVIDIA's Windows 7 video drivers, no improvement.Disabling the HD Audio in device manager seems to help a lot of people, I don't have this in my device manager.Sound drivers/devices also seem to be a leading source of CPU over-usage in a lot of cases. I've tried disabling/removing my sound card, drivers, and audio services to no avail. I initially had a sound card and on-board sound (AC97) running and disabling one of the two had a minor improvement in performance but nothing spectacular. Even with both disabled the CPU usage still spikes to 90-100% during video play, not to mention the video stutters and stops often.I also had on-board LAN in addition to a wireless card installed so I've switched between the two, disabling one or the other with no marked improvement.Setting the page file to manual control with a 4+ GB size setting, no difference.Disabling AERO, using a Windows 7 classic theme, no dice. I like to think that my hardware is strong enough to handle video streaming/playing without maxing out the CPU but if you think I'm mistaken then feel free to let me know. My WIN7 performance score was somewhere around 3.4. I've also watched the Process Explorer extensively and I can't find any service that sticks out terribly. Any ideas? Any diagnostic tools you guys would recommend?