Lag is affected by ping times...
you will get the same experience on 1Mb as on 4Mb.
Lag on xbox and PS3 is normally cause the games are hosted in the UK or US. 200-400ms
reason why I swapped to PC gaming...15-50ms...
hope that helps.
But yeah...was aon 10,4,2,1,512,384...been there done that...