I run a Radeon 6450 on an i7 quad-core with Win7 64 and 4Gb RAM. The game's performance is good, except for occasional FPS drops in these conditions:
1. Tactical battle, grassland (can't identify any other reason for FPS slowdown than that)
2. Fog of war that seems suddenly thicker than it was before.
For item 1, the FPS slowdown can disappear both during and after the battle.
For item 2, if I quit the game and re-start it, the slowdown disappears.
