Programming with DirectX 12 (and Vulkan, and Mantle) is a much different process than most developers are used to. The biggest change is how work is submit to the driver. Previously, engines would bind attributes to a graphics API and issue one of a handful of “draw” commands, which turns the current state of the API into a message. Drivers would play around with queuing them and manipulating them, to optimize how these orders are sent to the graphics device, but the game developer had no control over that.
Now, the new graphics APIs are built more like command lists. Instead of bind, call, bind, call, and so forth, applications request queues to dump work into, and assemble the messages themselves. It even allows these messages to be bundled together and sent as a whole. This allows direct control over memory and the ability to distribute a lot of the command control across multiple CPU cores. Applications are only as fast as its slowest (relevant) thread, so the ability to spread work out increases actual performance.
NVIDIA has created a large list of things that developers should do, and others that they should not, to increase performance. Pretty much all of them apply equally, regardless of graphics vendor, but there are a few NVIDIA-specific comments, particularly the ones about NvAPI at the end and a few labeled notes in the “Root Signatures” category.
The tips are fairly diverse, covering everything from how to efficiently use things like command lists, to how to properly handle multiple GPUs, and even how to architect your engine itself. Even if you're not a developer, it might be interesting to look over to see how clues about what makes the API tick.