I'm not entirely convinced that lag is the only problem, but I will say that the mouse problems are the primary reason I sold my current-gen 13" Macbook Pro a month after buying it. It was simply unusable with a mouse.
The reason I'm not convinced is that my old Macbook Pro running Tiger had the exact same issues, but a proprietary mouse drive called USB Overdrive X allowed me to remove the acceleration, and the mouse felt perfect. That driver apparently didn't work in Lion (or Snow Leopard), and every single script/setting/utility I could find for supposedly disabling acceleration didn't change anything except perhaps speed (sensitivity).
The reason I'm not convinced is that my old Macbook Pro running Tiger had the exact same issues, but a proprietary mouse drive called USB Overdrive X allowed me to remove the acceleration, and the mouse felt perfect. That driver apparently didn't work in Lion (or Snow Leopard), and every single script/setting/utility I could find for supposedly disabling acceleration didn't change anything except perhaps speed (sensitivity).