The only other suggestion I can make, and I don't know how to do this myself, is to make sure the game is using the right graphics processor. If your i5 has an integrated GPU and you're using a dedicated one as well, I've seen reports where the wrong GPU might be chosen for some applications. While I'm running the i3 GPU pretty well (20-25 fps for an HD 4000), maybe your i5 is an older model.
Also, make sure you're not in some power saving mode. I have a Lenovo i7 laptop at work, and it won't use full turbo mode unless its plugged in. I also had some power settings on the Intel GPU at home that I set to full power while plugged in