Have you tried tweaking your current laptop, like disable visual effects, end processes you don't need?
Setting your GPU to performance mode.
I know that when I played NFS Carbon for like 2 hours, suddenly it became so laggy I couldn't play so I had to turn of the game. When I got back to windows, YouTube HD video became choppy and out-of-sync. I've formatted it, installed a fresh new Windows, installed the drivers that came with it - the same problem..
And when I try to update the radeon drivers, it doesn't detect this GPU (it gives me some kind of error when I turn on AMD Vision engine control center, so I had to downgrade it to the stable version of drivers)