Sounds like your CPU usage is high.
Try some of these things:
Press Win Key + R and type msconfig into the box that pops up. Press enter and you are presented with the System Configuration Utility. Click on the Services tab, and check the box that says "Hide all Microsoft Services". Now uncheck all the services that seem unnecessary. Such as Windows Media Network Sharing (Unless of course you do use WM network sharing). Google Updater, anything that you think shouldn't be running unless you want it to be. When you've done that you can click on the Startup tab. Expand the "Command" column so that you can see the location of the file. Again, uncheck everything you deem unnecessary. Click apply and it will ask to reboot your computer. Do so. When you start up again a message will pop up saying that you just changed start up programs. Check, "Never Show Again", or whatever it is, and click okay.
If that doesn't work, try downloading and using the free trial of
TuneUp. Run every test or optimization and your computer should speed up a treat. You could also try "Process Explorer". Google it.
And of course some would argue,