For a computer that costs thousands of dollars. Is that too much to ask that Apple make proper drivers for the one new model of discrete graphics cards they ship every year?

I’ve talked about this with one of the guys at Apple who writes graphics drivers. Basically vendors give them their Windows drivers and they change them to work against IOKit. No idea what my point is, besides, “it’s probably not that easy”. But they are on the Vulkan team and probably now have experience providing a similar API, so I’m hopeful the Macs get great adoption for Vulkan.

Remember that for example nVidia uses exactly the same codebase for Windows and Linux, and Linux gets same performance as Windows with OpenGL.

It's surely not easy, but that's still an important task. Hopefully El Capitan will also optimize these.

OSX renders UI with OpenGL - and now in El Capitan it will render using Metal. The performance overhead affects more than just games.