The present technology relates to biocidal compositions and methods that contain and utilize at least one biocidal agent and at least one potentiator system wherein the resultant combination has an enhanced biocidal efficacy. The present technology also discloses a rapid screening assay for determining biocidal compositions with enhanced efficacy, e.g., a microbial contact kill time of 5 minutes or less. Further, the present technology provides a method of determining biocidally effective concentrations of biocidal compositions comprising at least one biocidal agent and at least one potentiator system.