BTW not sure what 4.1 and 4.2 do - unless it’s to delete any images to see if there was one causing the slowness.
Paste and Match Style strips the text to plain-text and removes the images, so yes it is an efficient way to remove all of the images in a section, which we then follow up with a test save to see if it was that section that was making things slow.
This is course why this test is being done on a disposable copy of the project. It’s merely to gauge whether or not this entire track of looking at images is worth continuing to look at.
May I suggest that I try this for a little while and then get back to you here if things are still slow - after working my way through your steps 1 - 4 (1, 2, 3), please?
Sure, but again like I say, if none of this has anything do with images then it would be a better use of your time to determine that first, rather than dividing your time between a task that presumes it is the problem, with a task that challenges that presumption.
If you look up the shortcuts for the Find Next Formatting, Select All and Paste and Match Style, you should find this experiment can be done rather quickly—at least to a point where you might determine things are gradually getting faster when you save.
I correct it by deleting back from the ‘E’, save it; but it re-appears on my next open.
I don’t know about that for sure, but it does kind of sound like a phantom list from what you describe. The usual methods for stripping out formatting and reapplying it should suffice.