why is my minecraft server lagging for everyone?

Answer 1

sounds like your hosting in your house

home broadband has a limited upload speed which means you cant send out information to other players fast enough, you wont be able to handle more than 2-3 other players before it gets pretty bad

only way around this is to get SDSL instead of the ADSL you have, but this is cunsidered a business line and will cost you alot more