Everything I have read recommends using stl vectors instead of c style arrays. But when a ran some tests of 100 million accesses of arrays and vectors, I found that the array part finished in 1 second and the vector part took 6 seconds. This was using the  notation with the vector. It took even longer with the at() notation. Is the difference in performance this large? If this is the case, presumably vectors are not the way to go if the program requires many accesses to an array?