Hash function question

Question

I'm working with hash codes for string objects. Here's the method i'm using (i think this is the same as the normal string hash function, except for mine supports skipping characters):
public int hashCode () {
        int h;
        h = 0;
        for (int i = 0, len = rep.length (), step = skip; i < len; i += step)
            h = h*31 + rep.charAt (i);
        return h;
    }This comes from a wrapper class that holds a string (REP) as well as an int SKIP that causes the hash function to skip characters in the string (my question won't be dealing with SKIP, ie, assume SKIP is one for the purposes of this question).
I'm running this hash function on four-character "words" of the form "xxyy" (where x and y are some value between 1 and a specified N, where N is by usage usually less than 300 or so) and also on words of the form xXyY (where x, y, and N are the same as before, and X=2^16 - 31x - 1 and Y=2^16 - 31y - 1).
So the question is, will this hash function take longer to run on xXyY words than it will on xxyy words? if so, why?

Answer 1

If X and x, as well as Y and y, are of the same type but merely hold different values, and the strings are of equal length, that shouldn't matter performance-wise.