My system is pretty high end (32 GB or RAM, i5-3570k, SSD HD, win7 64 bit, Radeon R 280X graphics) and I can confirm that while the game runs buttery smooth maxed out, I can hear the fans on my video card spinning up under load and that hardly happens with any of the other games I play.
In any case I suspect there's a few more optimization passes that could be done and hopefully we'll see some improvement in the near term.
Beyond that, The game has been super fun and it was well worth the money.
