Multiwire proportional chambers (MWPCs) are widely used in many different disciplines. The quality of the results depends on many factors such as gas gain, detector count rate, detection efficiency, spatial and energy resolution, and uniformity. We report here on a detailed study on how to optimize all these features, in particular regarding the use of MWPC at synchrotron radiation sources. Detector behavior has been analyzed in relation to geometry of the wire planes; electric field; frames design and window geometry; and gas parameters. From this study, general optimization criteria were obtained. The results of this study have been applied to produce a new design for a detector required to perform time-resolved X-ray diffraction/scattering experiments in the submillisecond time scale with a spatial resolution of 0.03 cm. In addition, we report on the outcome of simulations aiming at understanding the influence of manufacturing defects as well as gas quality.