janp: OneNote's API model is that you read the whole page, make necessary changes and write back the whole page. Also trying to find the selected paragraph requires reading all paragraphs and checking each of them to see if it is selected. So your experience that it takes long on large pages is normal. For editing dates/times, this isn't expected. I can't say why without knowing the details of the macro.

Hi Omer. Could you please say something to my question below - the first one?
This happens with lots of macros, and I find it extremely irritating to lose all my editing hints (author, date, time) in a complete page when using a macro only on a certain paragraph ...
Thx!

Is it possible to have this macro handle only the selected paragraph? If I use it on a selected paragraph it first of all takes long in pages with lots of text, since it seems to check every paragraph in the page. And secondly it resets the editing dates/times of ALL paragraphs in the page to now, which I definitely do not wish to happen!!

Another (not so important) question: How come that I can put certain macros on my toolbar as a button and others only as part of a drop down menu (in this case drop down menu called "Tags"). It needs more clicks and more mouse action to reach a tool in the second case.