Universities have to cope with scarce resources and nevertheless are expected to achieve excellent results in research, teaching, and third mission. Therefore, efficient resource use is of great importance. This paper explains emerging concepts and requirements of efficiency analysis, connecting it to university rankings. In order to achieve efficiency improvements, dynamic timeseries analyses are important and helpful in order to understand developments and effects in university processes and structures. The longitudinal efficiency analysis technique DEA Malmquist index is presented as application example with THE and Leiden ranking data for 68 European universities 2011-2016. Results demonstrate an improvement potential of up to one-third and a very diverse distribution of dynamic efficiency changes among institutions.