Wifi issues OSX 10.10 x 10.9 x 10.8...

I`ve been moving and testing all the latest OS X and the sentence is: I can only get my full internet speed (60Mbps - download) on Mountain Lion, which is the OS that came installed with my MacBook Air mid 2013.

Aren`t the latest OS 10 really not as sharp and tweaked as the cats?

This is sad.

Tested right now:

3593209770_medium

via www.speedtest.net