Well, what I don't understand Crazyinsomniac, is why this should take so long, to build the matrix I mean. Accessing the data is lightning fast, it's just that looping through the hash that is rough. Question: if I made my data into single entry vector tables, and then looped through the vector and loaded it into the matrix, maybe that would help? I don't want to go to C, because this code is just the beginning of much more complicated stuff, and I need perl's structures I think.