Looks like something is hogging your CPU to me, you sure nothing is running in task manager thats using 100% cpu or loads of ram? sometimes programs dont close properly and they still run in task manager and slow down your system.
I've had the same problem as you before a few times.
I'd make sure something in the background isnt messing it in like a program or anti-virus.
Also for some reason if I dont close internet explorer or chrome my games lag, I have to make sure they're closed before I launch a game.