Thank you for your suggestions. The document most affected ( which is to say, the one in which I've been most aware of this issue ) is already saved in .docx format. I very rarely ever use spell-check, and never 'as you type'. As regards using styles for formatting, I must confess I've never really played around with styles very much; but that apart, there are a lot of different formats within this document, and I suspect that setting each one up as a different style might prove even more cumbersome than just waiting the twenty or thirty seconds while it does it's thing each time. Which is not to say that I'm embracing the idea of waiting twenty or thirty seconds while it does it's thing each time ...!

I haven't tried working in draft view; I'll give that a go today and see if it helps.

The thing that occurs to me is that this problem has only reared it's head in the last week or so, which makes me wonder why ...?

Other than that, any and all other suggestions or thoughts still welcome, and I'll keep you posted as to developments.