''control pannel'', ''sytem'', ''advanced options'' ''settings'' (the top one) then you will see tick boxes! click the on that says ''ajust for best perfromance'' and also next to it will be '' it will say ''advanced'' and at the bottom it will say ''virtual memory'' which is virtual ram! change the virtual ram it will have ''inital size'' which u should change to 3000, then maximum which should be changed to 4000, this just increases ur virtual ram so you're graphics has more of a performance with out you're normal ram being used for windows (:
one more thing, if you know how to do this then when you first turn on laptop go to ''bios'' then the option graphics settings, some where it'll have the power of the graphics that it is running at, if its running lower then what it can handle, then change it to its maximum handle!
i have done all these options on my computer and hardly ever lag any more (:
but the changing the virtual memory size is the best option if you dont want to acess you're bios (: