Energy dispersive X-ray spectrometry has the potential for making very rapid analyses of multi-element samples. In order to fully exploit this capability several studies have been carried out with the goal of improving performance at high input count rates. A refined amplifier permits operation at input count rates up to 80000 per second with minimal peak shift and distortion. Optimum choice of tube parameters and filters permits utilization of a single Mo transmission target tube to analyze a broad range of elements in minimum time. Use of a pulsed tube further reduces the time required for analysis without sacrifice of precision or resolution. Dead time necessarily increases with increasing input count rate. It can be reduced by selecting a short amplifier time constant, but only with a loss of resolution. Digital processing permits recovery of the lost resolution. Some illustrations are given of spectra that have been processed on-line using a computer based multi-channel analyzer.