The PC version of Tomb Raider has just received a patch, according to a recent post on Steam The updates fix "a variety of issues that we either found out about shortly before release or immediately after."
The main problems that the patch is covering are "stability and start-up issues" for users running Intel or NVIDIA graphics components. This is good news for NVIDIA users especially, as last week the company had to go as far as apologize for the poor performance of GeForce GPU's when handling the game. Apparently, NVIDIA hadn't received the final game code until this past weekend, which made it tough for them to optimize the game's stability and performance.
The Steam patch notes also explain that "while we expect this patch to be an improvement for everyone, if you do have trouble with this patch and prefer to stay on the old version we made a Beta available on Steam, Build 716.5, that can be used to switch back to the previous version. Please note however that you can only play multiplayer with people that share your version."
A full list of fixes can be found in the patch notes on the official tomb raider forums.