Hello Adam,
Currently we are trying to reproduce the considerable difference in processing time.
The difference in 20-25% that you are observing on benchmarking set, actually can be expected due to the changes in the depth maps generation procedure implemented in 1.5. These changes should result in more accurate depth maps.
But 200-300% slow down shouldn't be expected and it looks strange. We are trying to check, if it could be caused by dual-socket CPU configuration or double GPUs used. Were you able to observe the same slow down on the large project, after re-installing Metashape 1.5 (if system reboot is possible, it may be also considered)?