Server lags after map change

[jacek2144]

Hello i have small problem. When map changes on my server and there is more than 3 or 4 players it starts lags when map changed and players joined to teams. Even i have lags( I"m hosting from my PC and playing in tf2 from my PC). Need help. I Don't know why it happens.
it Lags for me like in this video : http://www.youtube.com/watch?v=f5Av2IcZywQ

[Mike]

That's why you shouldn't be hosting from the same computer you play on.

[jacek2144]

So its lagging to everyone even me because i'm playing on same pc. So pc needs more memory but i have launched tf2 that uses most of memory so thats why it lags ?