For very large list, it can be a challenge to save an order list. Something this can take a while, on certain hosts it can be stopped from execution returning an 500 server error. The main cause for this is a php environment variable called Maximum Execution Time. This is generally set for 30 seconds.
When Pagination is set for Advanced Post Types Order plugin, the timeouts are no longer a problem, the sort list save job is split into small chunks to allow server to process the data.
Additionally, a progress data is being show, the current chunk page out of total jobs.