In this paper we characterize the spectroscopy performance of a new high resolution electron energy-loss spectrometer for transmission electron microscopy, recently installed in our lab. With the event of commercially available monochromated transmission electron microscopes, equipped with improved spectrometers, experiments became feasible that allow the study of chemical bonding and electronic structures of atoms and solids at the nanometer level with an energy resolution in the range of 0.2-0.3 eV. This significant enhancement in resolution, however, can only be fully harnessed with an optimized microscope and spectrometer setup and in a suitable local environment. We attempt to quantify some of the limiting factors on our system with emphasis on spectrum mixing, spectrometer aberrations and transmissivity and we sketch proper working conditions in order to achieve the desired performance.