There seems to be more to the graphical issues surrounding the PC version of Tomb Raider than simply poor performance on nVidia cards. There is a big difference in special effects when you compare windowed and full-screen modes together. I didn’t notice the issues at first, but when a friend mentioned it on Steam I couldn’t help but do some digging. Lens flare and bloody and water dripping onto the screen seem to be present when playing windowed, but not full-screen. I’ve taken two screenshots myself which you can see after the break highlighting the lens flare issue.
There is a thread on the Steam game-hub showing off a wider range of images highlighting the issue. On the official forums there is a thread about the issue as well with a developer representative saying that it is being investigated. People are reporting the issue on both nVidia and AMD cards.
My graphics settings are at a default setting of High in both shots, just one is windowed and the other isn’t.
You can even see the issues on the main menu, the windowed mode has water droplets on the screen, the full-screen mode doesn’t.