I recently noticed a very annoying thing. Normally I only work with my MacBook but since my desktop pc currently hast no graphics card I was forced to use my mac for gaming as well.
In most games, you will not notice any problems. But when playing StarCraft2 which is a very fast game und you really need your mouse speed, you will notice a huge mouse input lag. When selecting any unit or just moving the mouse cursor it laggs like about 100-200 ms (in my opinion, its not measured, just how I feel it).
There is also another annoying thing if you don’t use the trackpad and a normal mouse with the mac, it’s acceleration… You simply cannot turn it off. I had a script for that to turn acceleration off, but that didn’t fix the input lag problem.
But there is a good solution for both of them! Its called SmoothMouse for OS X. I can highly recommend it. Now gaming feels like on a Windows PC! No lag at all!