A data layout optimization may utilize affinity estimation between pairs of fields of a record in a computer program. The affinity estimation may be determined based on a trace of an execution and in view of actual processing entities performing each access to the fields. The disclosed subject matter may be configured to be aware of a specific architecture of a target computer having a plurality of processing entities, executing the program so as to provide an improved affinity estimation which may take into account both false sharing issues, spatial locality improvement and the like.