X3: Terran Conflict
Here's a rolling demo of the game:http://www.egosoft.com/download/x3tc/demos_en.php
I've only tested the rolling demo on my PC, I have not played the game yet. I am still playing the previous game; X3: Reunion.
Regardless of what resolution and graphics quality settings I use (HD 5850), frame rate changes very little. Overclocking my Q9450 resulting in improved frame rates.