While AMD advertises Mantle as a nice way to reduce driver overhead, Nvidia's technology specialists propose similar gains using OpenGL extensions. The presentation shown at Steam Dev Days outlines the way extensions should be used and their performance gains.

While it all looks very interesting and promising, it will not be an easy performance update anytime soon. The correct implementation of these features is not easy and can reduce performance in the worst case. Another issue at the moment is the lack of OpenGL support among game developers. Almost all PC games use DirectX these days, however the more widespread adoption of gaming Linux due to SteamOS may improve matters. It will be interesting to see how well these OpenGL features will work with different graphics cards and how soon will we see the first practical examples.