Paging - What can I do with it? Please read

My server war running good on previous versions, but since 1.2 I have problem with PAGing.
This occurs every x seconds (maybe 15) and causes small 1 second lags.

We have 80 slots server, in afternoon there are from 40 to 60 players online.
World and plugins are running on RAMdisk. Our i5 is always under 200% of usage.
Backups and Dynmap are on normal HDD.
Server is running on 1.2.4.R1 (some plugins don´t work on 1.2.5).
4GB RAM is allocated to the server.

Linux minecraft 3.0.0-15-generic #26-Ubuntu SMP Fri Jan 20 17:23:00 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
java version "1.7.0"
Java(TM) SE Runtime Environment (build 1.7.0-b147)
Java HotSpot(TM) 64-Bit Server VM (build 21.0-b17, mixed mode)

This is start.sh

Code:

/usr/lib/jvm/jdk1.7.0/bin/java -d64 -server -Xmx4G -XX:UseSSE=3 -XX:+UseLargePages -jar craftbukkit-1.2.4-R1.0.jar nogui

Did anybody have this problem and solved it?
Do you have any solution for me?
I can try anything you say that can help and I can provide more info.
Thanks

 

This occurs every x seconds (maybe 15) and causes small 1 second lags.
Java garbage collection?
I know there are lots of settings for java, you can for example say how many threads for garbage collection, maximum duration, ....
There's a thread on these forums about running your server with more commands, you might want to chack that out.

 

Bertware
I tried some settings but the only result was that with 20 players Java used 5GB RAM

 

I'm using

Code:

-Xms128M -Xmx2048M -server -XX:PermSize=128m -XX:MaxPermSize=256m -XX:+DisableExplicitGC -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+UseNUMA -XX:+CMSParallelRemarkEnabled -XX:MaxGCPauseMillis=50 -XX:+UseAdaptiveGCBoundary -XX:-UseGCOverheadLimit -XX:+UseBiasedLocking -XX:SurvivorRatio=8 -XX:TargetSurvivorRatio=90 -XX:MaxTenuringThreshold=15 -XX:UseSSE=3 -XX:+UseFastAccessorMethods -XX:+UseStringCache -XX:+UseCompressedOops -XX:+OptimizeStringConcat -XX:+AggressiveOpts -jar "c:\craftbukkit\craftbukkit.jar"

Those settings with GC are for Garbage collection. these arguments are calculated by my GUI, so don't ask me what evey single thing does. (I knew it, and I will know again soon as this code is going to be rewritten)
However, this thing holds 5 players at 370MB (my test server)

 

Hm..
Bertware
And you main server? What are you using there for how many players?