Problem Server lags for a friend

[Matan2013]

Hello everyone my server is lagging not for me but for a friend Im using direwolf pack and it worked fine for an hour and than it started lagging for my friend. I tried restarting the server, making a new world, removing the server completley and reinstalling it.

This is what I have:
Intel(R) core(TM) i7-2600 CPU @ 3.40GHz 3.70GHz
and 8.00 GB RAM
This is the command im using to launch the server

java -server -Xms4G -Xmx6G -jar ftbserver.jar -nogui

How can I fix It?

 

[heggico]

If you are not lagging, then it's not a server issue, or do you run the server on your own pc? Then it might be your internet connection.

 

[Matan2013]

If you are not lagging, then it's not a server issue, or do you run the server on your own pc? Then it might be your internet connection.

well the server is on the same computer as the game but when we play tekkit its not lagging so it has to be something in ftb

 

[glasspelican]

when your friend starts lagging have him hit f3 and look at what the memory usage of his client is if its more then 50% he will want to use the advanced panel in the launcher to allocate more ram