At start-up, the tasks reads several header keywords of the input files in order to establish the stacking parameters and to sort the input files. The I/O performance of the CFITSIO library, which is used to open the FITS files, strongly depends on the file size. Users are recommended to filter the event lists before running edetect_stack, if they experience performance issues.
At runtime, the performance strongly depends on the number of images to be processed. The number of pointings, which are combined in one call to edetect_stack should be limited to the absolutely necessary. Large mosaics should be split into several regions which are processed separately. Correspondingly, users can divide the field of view of repeatedly observed pointings into smaller areas, process them separately and combine the output source lists.
Pseudo exposure IDs set by emosaic_prep should be below 110100.
