In my experience, Revision Tracking is a resource hog and editing documents with lots of tracked revisions always slows down things.

If this is a recent problem then it could be related to something else. Like maybe if you changed your default printer around the time you started noticing the slowdown. Word continually repaginates based on a printer driver so that might be something 'non-Word' to investigate.

If you haven't kept the document clean with formatting largely done with styles then Word needs to do more processing to keep it WYSIWYG.

The spell as you type is on by default - if you wiggly red or blue lines under misspelt words then it is turned on.

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Andrew Lockton
Chrysalis Design, Melbourne Australia