Thanks for your answer!
About how many collisions are we talking about? The problem could be that the hash_map has a small range of keys to assign hash codes to, or it may be that you are using a bad hash function.
There are probably thousands of collisions. I am trying use tripel of short values as key...and therefore I convert the three short values to a long value. With n=300 there are n^3 = 27 Mio possible tripel, and probably 1 Mio is actually saved in the hash table. Since the running time is amazingly low I guess there are at least some thousand collisions.
As hash function I am using the stdext::hash template function, and I do not really know how large the range of the keys actually is.
I thought one of you might have used this hash_map and the hash function before and you know how to increase the range of the keys of the hash codes.
An alternative would be another hash_map / function where I could set the hash range by hand.
Sebastian