I recently created a tiddler with the following text:
<$text text={{{ [!is[system]get[text]splitregexp[\s+]count[]] }}}/>
Returning the word count of the entire wiki. What I’m wondering is if there might be any potential downsides in terms of performance from retrieving all tiddlers in this filter run?
One key issue is when do you see it?. If always visible such as in the sidebar it will always be recalculating. See Control Panel > Info > basics and scroll to the bottom of the tiddler where you see;
These are a little less complex than word counts but still global, they are fine because they are only “computed when rendered”.
You could add a toggle that hides the count unless clicked.