The visualization tool rdvis is presented which aims at helping the programmer to find program transformations to improve temporal data locality. We present a number of locality metrics that capture the necessary information. Based on a cluster analysis of basic block vectors, the tool gives strong hints on which program transformations are needed. The visualizer allowed us to find the necessary transformations for three SPEC2000 programs in just a few minutes. After performing these transformations, the programs run 3 times faster on average on a number of different platforms.