This paper reports on the characteristics and use of a new mode of measurement: High Performance DSC (HPer DSC), which represents a major step forward in high-speed calorimetry, as compared to standard DSC. It facilitates the study of the kinetics and metastability of macromolecular systems, especially the analysis of rate-dependent phenomena in real time. Controlled and constant scan rates at hundreds of degrees per minute and combinations thereof both in cooling and in heating are possible. Heats of transition, heat capacities, temperature-dependent crystallinities, etc. can be established at the extreme rates applied. Examples of the utilization of HPer DSC are given for polymers with respect to the effective hindrance of crystallization and cold crystallization, avoidance of recrystallization and the rate dependency of vitrification and devitrification. Low, milligram-scale sample masses, even down to the microgram level, are utilized. The short measuring times also provide the high throughput needed in combinatorial chemistry.