Confirm there is still a bug in the 1.2.3 version available for download. Tried stacking 837 images and the difference is noticeable; 1.2.1 finished in 28 minutes, 1.2.3 was only about 25% complete when I force quit at 3 hours. Initially appears something with thread & memory allocation as a first difference, only half the allocatable memory was used in 1.2.3 vs 1.2.1. Despite showing 8 threads are available only appears to use 1 thread during stacking. Would love to help more to troubleshoot.