Apple's QA has really gone downhill lately. First, they break bluetooth hands-free with iOS 8.0.2, and now the initial 10.10 install breaks 5GHz for me on a Mid-2012 retina MBP. If I connect to 5GHz, it's extremely slow. If I go to speedtest.net, the page loads slowly. Once I attempt to start the test, it will not run. It just hangs. On 2.4GHz, speedtest.net works fine (although obviously the results are slower). Any suggestions? Are there any plist files or something else I an reset? I've done the following: 1. Repaired permissions and rebooted 2. Deleted my saved wifi networks and readded them 3. Turned wifi off/on. 4. Attempted to change my DNS to google DNS when I originally noticed the slow down.