I go to task manager and kill anything running that I dont need. Since I have an HP Pavilion there’s a crap load of background processes running. I dont kill my antivirus but I do turn off the WIFI when gigging. Running Windows 7 I also change the Personalize settings to the very basic Windows XP visual style. No fancy menu options or visualizations. No screen saver either. Also I go to My Computer/Properties/Advanced settings and changed the Cache size and also set the option to “Background services” instead of Programs. I read that Windows treats audio as a background process which is stupid but changing this helps. I dont know why people Defrag a hard drive often because that isnt necessary unless you are adding/deleting/moving large bulks of files around or adding/removing programs alot. This cant be a regular thing and the analysis will tell you if the drive needs a defrag or not. Also under the My Computer settings there are 3 options, Best Appearance, Performance, Custom. I set this to custom and turn off everything but a few options. Windows can be very pretty to look at but all that animation takes up CPU power. The only 2 problems I run into is the fan is almost always running which seems to be an HP defect. And my audio driver sometimes gets crappy and I need to switch the USB port that its connected to. I use an Audio Kontrol 1 and all software is updated so I think its just an issue w/ this PC model.
Lastly, I dont reboot often. That used to help alot when Windows wouldnt release resources from RAM when a program closed but thats not as big an issue anymore. I also remove the battery when at home.