When Word crashes or runs very slowly, this could be caused by the Reviewing Pane. Due to the number of changes and comments, there is a lot of content in the Revision Pane, which causes Word to run slowly and possibly crash.
The Reviewing Pane is the Pane on the left side of your screen that you can extend when you go to the Review tab.
Close this Reviewing Pane while you keep on working on your document.
If this does not solve your problem, please contact Scribbr via the chat or send an e-mail to info@scribbr.com.