Ever since upgrading to Mountain Lion, I’ve been suffering from the “slow wireless net” problem that plagues some people. None of the fixes I’ve found suggested on the Internet have worked for me; I just got consistently shitty internet on my Mac, especially at home.
Today, I was poking around in my Airport’s settings and switched it from 802.11n (802.11b/g compatible) to 802.11n only (5ghz). And that seems to have ACTUALLY WORKED. Though the true proof will come a few days later, after I’ve slept the machine and woken it back up – more than once, disconnecting and reconnecting the wifi would make it work for a while, but not forever.