ElasticSearch Server load on start

Hi everyone,

I've been asked to implement Elastic Search for use on my company website.
So I installed it on my computer. And all seems to be working well locally.
When I asked some admins to install Elastic Search on some servers (integration and production servers)
They found out that launching Elastic Search binary instantly raise the server load and CPU charge.

I've found tons of example but I'm talking about only one server, no index, no type and no document whatsoever. So I wondered if this wasn't Java's fault.

And when checking the java versions on my computer and the servers, I found this :

My computer :
java version "1.6.0_27"
OpenJDK Runtime Environment (IcedTea6 1.12.5) (6b27-1.12.5-0ubuntu0.12.04.1)
OpenJDK Server VM (build 20.0-b12, mixed mode)

Server 1 :
java version "1.6.0_26"
Java(TM) SE Runtime Environment (build 1.6.0_26-b03)
Java HotSpot(TM) Server VM (build 20.1-b02, mixed mode)

So our Java versions are very similar (not likely to be the source of the problem). But our Runtime Environment are different.

I was wondering if this could be the source or if I'm mistaken.

My english is not so good so I hope you get it all. If not please feel free to ask for anything.

Thanks !