how many hours are required for PSE 13 to load previous backup of 80,000+ items

94287  wrote Yesterday started incremental backup of current PSE 13 84,949 item catalog. The previous backup was a full backup of 3/2017 PSE 13 catalog. It will soon have been 24 hours of seeing "Please wait while previous backup is being loaded....". Please advise whether to continue waiting or "Cancel". Thank you for any assistance. Jerry

If I understand well, your goal is to do an incremental backup, you are not trying to do a restore.

It's not normal to wait so long to do an incremental backup. The process to "load" the previous or first full backup works from the catalog database and the .tly file in the backup folder. Comparing those databases and .tly files should not be so long; no copy of the saved files in the backup folder are done, but relatively big temporary files are created in the process.
I don't know what makes the process freeze, but there is no risk to kill the process. I would try to do a new normal full backup (a few hours depending on the file sizes and your hardware).