WYSIWYG seems to add a lot of new carriage returns on edit. With a few round trips, this means more and more space appears in the page (ie it doesn't happen once, it keeps happening).

Create a page like this (wiki notation):

This is a quote

This is a paragraph.

{note}This is a note{note}

This is another paragraph.

Now save it. Now see what it looks like (HTML). Now edit it as WYSIWYG and just save it again. Now see all the added whitespace. Now edit as WYSIWYG and save it again. More whitespace. Etc etc.

{note}

and

macros are particularly obvious examples of this bug.