Quoting from the blog post: "We’ve been working with NVIDIA, AMD, and Intel to improve graphic driver performance on Linux. They have all been great to work with and have been very committed to having engineers on-site working with our engineers, carefully analyzing the data we see. We have had very rapid turnaround on any bugs we find and it has been invaluable to have people who understand the game, the renderer, the driver, and the hardware working alongside us when attacking these performance issues."
Leaving aside the amazing fact that Valve is achieving higher FPS on Linux than on Windows, the great thing about efforts like this one is that we can all expect the Linux desktop to become even smoother, faster, more seamless. I love it!