As you rush to explore the floating of Columbia, don't be too hasty. Nvidia yesterday released new graphics card drivers which can boost BioShock Infinite performance by up to 41% (with certain system and settings, obviously), so you'll want to install them. The 314.22 WHQL drivers also boost Tomb Raider framerates by up to 71%. Gosh! If you have an Nvidia card, you'll want to install these.
Nvidia has whipped up all sorts of fancy graphs showing the spread of performance improvements over the last set of certified drivers. They're tested with specific settings so you may not see quite such large improvements, but either way it's good news.
As ever, the drivers are up for download on the official GeForce site.