App engine Java: Sum difference two arrays - How to improve performance?

Question

I have a function in App Engine java where I compare two patterns stored in an int array.

Below is the code:

public static int patternMatch(int [] pattern1, int [] pattern2, int range) {

    int max = range * pattern1.length;

    int match = (pattern1.length - pattern2.length) * range;

    for(int i = 0; i < pattern2.length; i++) {
        match += Math.abs(pattern1[i] - pattern2[i]);
    }

    return (max - match) * 100 / max;
}

I am facing very weird problems with respect to performance of this function between the development server and deployment on app engine as listed below:

1. This function is called in a loop with the intention of finding best match(es).
2. Performance for a single iteration is critical as there are lot of iterations.
3. If I were to not have any logic in this code and directly return any integer, my overall code takes 100 ms to complete on an average.
4. The above code takes anywhere between 200 - 600 ms.
5. On the development server, if I replace "int match = (pattern1.length - pattern2.length) * range;" by "int match = Math.abs(pattern1.length - pattern2.length) * range;", somehow the performance improves bringing the time taken down to 200 - 300 ms only. No impact on deployment server.
6. If I remove "Math.abs" the performance improves bringing the average to 150 ms.
7. I tried replacing Math.abs with bit operations to derive absolute value. I see huge performance improvement on development server ~160 ms. On deployment server it makes things worse ~700 ms.

What I would like to know here is:

1. Why and how differently do Development server (Windows 7/eclipse/JDK6) and Deployment server behave in terms of performance tweaks?
2. Is there any better algorithm to the match?

Am stumped. Any help appreciated.