Waiting patiently for the Linux release... ;)
I only switched to Civ V from IV because it has a Linux version (and Civ IV does not, though it does run reasonably well under Wine, though I hate the fiddling required to keep Wine and GPu drivers happy through OS upgrades and such). Civ V runs as well under Linux as it does under Windows; not perfect, mind you, but it's not perfect under Windows either.