http://support.microsoft.com/kb/331406#XSLTH3131121122120121120120
There is the problem. 1 AI player takes up the same computer resources as 2 human players. It basically maxes out my CPU and RAM, then the game freezes.
I'm on 3ghz with Hyperthreading and 1gb of ram, with cable (840kbit/s upload speed max).
So when we play, its usually 2-3 human with 2-5 AI, no wonder why it lags so bad. From now on its human v human.
The number of units and buildings, maxes out my computer and causes it to lag because it cant track that many units at one time, that and with AI taking up twice, hopefully this will stop the lagging, no more AI.
Now on LAN, it doesnt matter, interenet doesnt affect games, each computer stores and computes its own data and shares on network, on internet, there simply isnt enough bandwidth, so the host machine does all the storing of information and computing for all the players data.
*edit* In 1 min of game play, at the climax, I use about .5Mbytes per min of upload, and 330Kbit per min of download. That is a lot, way more than CS.