The biggest part of the fifth PC patch for Rise of the Tomb Raider game is the added support for DirectX 12. In a developer blog from Nixxes, the newest DirectX 12 support allowed the developer to spread the CPU rendering work over all CPU cores and without additional overhead. According to the provided benchmark results, DirectX 12 support allowed the same scene in the game hit up to 60 fps, while DirectX 11 barely reached 46 fps, all on the same configuration.
The newest DirectX 12 support also brought asynchronous compute, something that developer is already using on the Xbox One and which should, at least in theory, give AMD a slight performance edge over Nvidia.
Unfortunately, according to benchmark results coming from Hardwareluxx.de, Rise of the Tomb Raider is actually slower when running on DirectX 12, on both AMD and Nvidia graphics cards and across all resolutions.
As noted, the new Rise of the Tomb Raider also brings support for Nvidia's VXAO, or Voxel-based Ambient Occlusion technology. Unfortunately, VXAO is still not detailed by Nvidia and it appears that it only works on Nvidia Maxwell GPUs and DirectX 11, as VXAO is not yet available on DirectX 12 from Nvidia. It is also only available on the Steam version of the game and not the Windows 10 Store version of the game.
The new patch also brings a couple of other minor optimization, fixes and tweaks as well as a new benchmark feature, fixed HBAO+ and other Ambient Occlusion issues and fixed motion blur problems in Stereoscopic 3D mode.
According to provided details, the patch is currently only available for the Steam version of the game while Windows 10 Store version should get it soon.