You are right, my question was indeed broader than background repagination. But repagination is I believe one of the main factors at play here, and when I got your reply that I'll have to work in draft mode in order to avoid all those hifi high-resource-utilizing auto functions of the program, then I thought well let me at least get rid of repagination and see how it runs.

Re the repagination box in advanced settings, I have disabled that long ago-- doesn't seem to keep MS Word from moving right along with its work of repagination. It doesn't appear to me that the check box does anything. It does its repagination just as much as it used to do before I unchecked that a couple of months ago.