Problem Direwolf20 5.1.x/FTBlite server pack lag issue please help

[Roehon]

EDIT Issues got better with a reinstall of Java from Java 6 to java 7 64bit but It still isn't right. I will say it's playable

hello,
I wouldn't really say its lag, Its more like all the players/animals/mobs seem to teleport step to step but the world seems(no block lag) fine. I've tried the Direwolf20 5.1.x and the FTBlite server packs and both have the issue. This is a small server that I setup for my autistic son and his friend from school so any help would really be nice. thank you

edit I setup a vanilla server and the lag doesn't happen in vanilla only FTB

pc specs
AMD Phenom II X4 965 Processor 3.4 GHz
4 GB ram
Nvidia Geforce GTX 460
OS Windows 7 64bit



this is what my server text file looks like
#Minecraft server properties
#Thu Feb 21 21:42:36 EST 2013
generator-settings=
allow-nether=true
level-name=world
enable-query=false
allow-flight=false
server-port=25565
level-type=DEFAULT
enable-rcon=false
level-seed=
server-ip=192.168.1.5
max-build-height=256
spawn-npcs=true
white-list=false
spawn-animals=true
snooper-enabled=true
hardcore=false
texture-pack=
online-mode=true
pvp=true
difficulty=1
gamemode=0
max-players=10
spawn-monsters=true
view-distance=8
generate-structures=true
spawn-protection=16
motd=A Minecraft Server

 

[Fij]

well i believe its the current modpacks, having problems i also have some weird problems with my server.

your server seems powerfull enough.

 

[Roehon]

I think you maybe right about the server pack, after the java update it got better but It still not right.
I can really see it when I use water in farms or lava, they don't move smooth and I get holes sometimes

 

[glasspelican]

Is the client running on the same computer as the server?
How may users are connecting to the server, and how many of them are connecting over the internet? LAN?

How much ram is dedicated to the server?
are you starting using the "server start.bat" or the .jar file?