Server Crash-Biomes'o'Plenty lagging me out generating new map

[WulleHerder]

So I just started a private 4 man server with FTB Unleashed and all the mods. I activated BIOMESOP in the server but now it seems that generating new map just lag-crashes the server. I have been looking all throughout the forum and elsewhere to find a remedy. I am a newb when it comes to servers, especially with so many mods. This is the first I have created with Unleashed. I threw on all the mods, removed the .disabled too. Other than generating new map, everything works fine, which is why i put the cause from BOP.

I have an AMD Phenom II X6 processor 3.20 GHz
12.0 GB ram
64 bit OS

Here is my Server properties file

Spoiler

#Minecraft server properties
#Sun Jan 05 22:29:18 PST 2014
generator-settings=BIOMESOP
allow-nether=true
level-name=World2
enable-query=false
allow-flight=false
add-biomes-to-default-world=true
keep-hunger-on-death=false
server-port=25565
level-type=BIOMESOP
enable-rcon=false
force-gamemode=false
level-seed=
server-ip=
max-build-height=256
spawn-npcs=true
white-list=false
spawn-animals=true
hardcore=false
snooper-enabled=true
texture-pack=true
online-mode=true
pvp=true
difficulty=1
gamemode=0
max-players=6
spawn-monsters=true
generate-structures=true
view-distance=10
spawn-protection=16
motd=

ServerStart

Spoiler

java -Xms1024M -Xmx4096M -jar minecraftforge.jar nogui -XXermSize=256m

I don't quite get what the Crash Report picked up, so if someone can pinpoint the error in that.
http://pastebin.com/Ri092yNM