How do I tell Writer to wait until a global operation (find-and-replace, say) finishes before reformatting the whole big document, instead of it reformatting and reformatting and reformatting and taking forever to finish?

In Microsoft Word, I tell it to find all places of two consecutive paragraph breaks and replace them with yyy, then I tell it to find all places of single paragraph breaks and replace them with a space, then I tell it to replace all places of yyy with two consecutive paragraph breaks. No matter how big the document is, this whole process takes just a few seconds.

In Writer it takes over half an hour. How do I tell Writer to wait until a global operation (find-and-replace, say) finishes before reformatting the whole big document, instead of it reformatting and reformatting and reformatting and taking forever to finish?

That’s a valid question, and I’d suggest to file it to LO Bugzilla as an enhancement request.

As a workaround, I’d suggest to try to switch to Web view for a time when you do such operations, and switch back afterwards.