Why does Word freeze on my long manuscript?

Settings that lighten a long file

Word repaginates, proofreads, and redraws markup continuously, and each of those grows with the document. On a full manuscript the pauses show up as a frozen cursor, a spinning wheel on save, or a scroll bar that jumps. Start with the settings, since they cost nothing:

• Draft view. View → Draft drops the page layout while you write. On Windows, File → Options → Advanced then lets you clear Enable background repagination, an option only offered in Draft or Outline view.
• Proofing. In File → Options → Proofing (on a Mac, Word → Preferences → Spelling & Grammar), clear Check spelling as you type and Mark grammar errors as you type (Check grammar as you type on a Mac). Check deliberately instead.
• Pictures. Select one, then Picture Format → Compress Pictures, clearing Apply only to this picture (on a Mac, File → Compress Pictures and All pictures in this file). Older Windows versions of Word can also show picture placeholders, under Show document content in the Advanced options; current Microsoft 365 builds may not offer it.
• Add-ins. On Windows, File → Options → Add-ins, choose COM Add-ins, and press Go to switch them off one at a time. Holding Ctrl while Word starts opens it in Safe Mode, which is a quick test of whether an add-in is the cause.

Tracked changes and comments

An edited manuscript can carry thousands of revisions and hundreds of balloons, and that is often where the freezing starts. Set Review → Display for Review to Simple Markup or No Markup while you work; Word stops drawing every change in the margin.

Once you have dealt with an edit round, save a copy with the marks intact (Novel – editor's changes.docx), then in your working file use Review → Accept → Accept All Changes and Review → Delete → Delete All Comments in Document. The working file becomes plain text again, and the copy keeps the conversation.

If the file itself is damaged

A document that has passed through many versions of Word and many rounds of editing can pick up damaged formatting. Microsoft's own troubleshooting advice is to copy everything except the final paragraph mark into a new blank document. In Word for Windows, Ctrl+End followed by Ctrl+Shift+Home selects everything but that last mark. Copy it and paste into a fresh file. If the new file is quick, keep it. If nothing helps, split the book into one file per part.

In Tabularia

Tabularia does its layout for the part of the page on screen, so that layout does not grow with the manuscript; the home page's benchmark gives the figures for that on-screen layout. Edits are kept apart from the text until you decide them: review changes and comments live in Markup Mode, and each chapter's word count is simply there on its Outline row, with nothing to repaginate first.

Bringing the book across is an ordinary DOCX import. Heading 1 starts a chapter, comments arrive as annotations where their anchors are clear, and tracked changes arrive as if accepted: inserted text comes in and deleted text does not. So accept or reject your editor's changes before importing if the decisions matter. Footnotes and endnotes arrive as notes tied to their references rather than as loose paragraphs. Tables and images are left out, and the import lists what it skipped. The return trip is clean by default, and a DOCX export can instead carry your pending Review Changes as tracked changes in Word when you check Keep Review Changes and comments as tracked changes.