Bizarre, bizarre problem. I'm at the point where I'm basically discarding whatever minimal expertise I have and starting with the assumption that I'm a retard and am doing something exceptionally obvious and stupid.
I'm using a Macbook Pro circa about last January, with a fully updated version of Mac OSX 10.4.10 and Windows XP on bootcamp. I'm connecting to an Airport wireless router. My problem is very simple: my network connection (bandwidth) is significantly slower in OSX than in windows. It seems to fluctuate between 1-50K/s in ftp downloads, and image loading in websites for instance is noticeably slower. In windows I can get 1m/s or better speeds and there is no lag whatsoever.
This is enough that it renders me entirely unable to play networked games (even local play in WC3) even though my ping in that case is something like 1-2m/s. I can play WC3 locally on windows perfectly. I get no packet loss no matter how long or hard I ping the router, and traceroutes show similarly peachy numbers.
I'm just recognizing how big an issue this is, since it has basically kept me from booting into OSX for literally
months.
Other computers connected to airport are functioning perfectly, including a Linux box. I
think my slow airport connection was ocurring in other networks as well, though my having this problem coincides with the installation of the airport router pretty perfectly.