CPU: Intel i7 4790 (Stock)
GPU: R9 295x2 (Stock)
RAM: Kingston HyperX Beast 16GB 2133CL12
Motherboard: MSI Z87M-Gaming
Storage: Samsung 840 EVO (OS)
Storage: WD 1TB 7200RPM (Game)
Display: Dell P2415Q 4K
VSync ON @ 60 FPS
On 1080p the game performed like a rock. Throughout the main game there were only three instances of glitches, one requiring me to suicide so the camera would zoom away from my head, another where a QTE in a tomb didn't resolve until a patch fixed it, and another where Lara would mysteriously not grab onto an object without being in a dubiously precise position. For the most part it ran like an absolutele dream, the only time it really did anything nasty was during a scripted event, as in the first case I mentioned I was doing a stealth take down. These were minimal, relatively minor, and by this stage are more than likely fixed by patches. My one issue was changing the game to 4K and then turning on triple buffering - if I alt-tab'd the game would crash indefinitely until killed it via task manager and then restarted.
For reference, you can see how your GPU will perform in comparison to ours with this set of charts.
NOTE: Precisely 50% GPU usage means only one GPU was put under load on the 295x2. This may indicate a lack of multi-GPU support.