Earlier quoted context omitted.
Safari is borderline unusable for me on 10.9 and 10.10. It will literally take 30 seconds to load facebook.com. If I open Chrome or Firefox and try it, it loads instantly. I've tried different DNS servers to no avail. I don't use Safari that often so I never bothered digging deeper.
Happens to me as well on a rMBP. There's also significant lag opening new tabs. I've had wifi issues on my phone since upgrading, where the iPhone will switch to LTE even though there's wifi available, from a network it remembers. Rebooting the phone will cause it to reconnect, so I'm trying this airdrop disable tip to see if it helps my connection problems.
I disabled AirDrop using the "defaults write" command, and now Safari loads things instantly! Holy crap!