Java SE (Java Platform, Standard Edition)

Here is my issue:
I am developing a web page as a server monitoring utility, and part of this project involves reporting the CPU usage for a UNIX (AIX, WebSphere 6) system.
My code works; however, the process I am using causes the CPU to go up 10% (every call) and take 500 milliseconds to perform.

My Code:
-->Using AJAX on a basic HTML page to call java step.(I would like to see this refresh every second and not see it hurt my servers performance)
Java Step:
try
{
Runtime rt = Runtime.getRuntime();

// Had to keep biting nails to figure this out this Unix command

String sVMCmd = "vmstat | tail -1 | tr -s '[:space:]' '[#*]' | cut -d '#' -f 15,16";
String[] cmds = {"/bin/sh", "-c", sVMCmd};

// Execute vmstat with # to filter out data we need

Process p = rt.exec( cmds );
java.io.InputStream in = p.getInputStream();
byte[] b1 = new byte[5];
in.read(b1);

String sFull = new String(b1);
String words[] = sFull.split("#");
us = words[0].toString();
sy = words[1].toString();
us = us.trim();
sy = sy.trim();

in.close();
}
catch(Exception ie)
{
oLog.error(ie);
us = "0";
sy = "0";
}

The Variables us and sy are set to properties later and then returned in XML for the AJAX.

What I am trying to do is return the "us" and "sy" from the vmstat command, I have tried parsing out what I need in my java and found that doing the parsing in my Unix command is much faster (Which explains my complex UNIX command). When I run the UNIX command on the sever it is quick and doesn't pose a issue as far as CPU usage is concerned.
I have broken apart my code step by step and have already determined that the " Process p = rt.exec( cmds ); " is the "Expensive part".
This is the only way I have found to return the CPU usage, and am looking for something quicker and less "Expensive" or a way to tweak what I already have.
I also use the getRuntime() Memory methods and they only take .003 seconds, something that fast would be great.
Any ideas?????