1. fedora updates his distro much more aggressive than ubuntu or debian does it
2. fedora 20 has the same mesa version I think?
so what did u think would have been changed much since fedora 19 (with updates), ok they use a newer kernel verison, but thats it, and for gaming that normaly should not matter that much.
But maybe I am wrong here, would be happy to get corrected with better information
Depends on the changes made in the kernel. Kernel changes that bump performance could be better memory management, DPM, or PCI-E changes, or there could be a few others but those were just off the top of my head.
Note, the stuff in the release notes about 'debug symbols' and slub_debug=- was copied over from the Alpha release notes incorrectly: Beta has a non-debug kernel, and the results should be fairly comparable.
The case with that one benchmark suite where f19+updates is massively faster than f20 seems odd; do you have any time to try and get a bit more detail there? I'd have to assume it's something wonky with the test setup or the benchmark itself, but it's possible there's something more to it...