Could you consider changing your forum statistics widget to make use of a longer cache time or use a combination of your earlier approach of storing it to a setting each time a new post is created and then also reset this every 24 hours or something? 

Problem is it takes 3.25 seconds for me. Meaning that every 5 minutes someones gotta wait that much longer for the front page (or any page it's located) to load. 

It would be nice if this was a backend cron job rather than a task that could affect page processing for a visitor. Anything that affects load time not directly related to that visitor should be updated via cron.

NOTE: I dont actually know if it is a cron job now or not, I presume you have cron tasks turned on.

Yes, it being a task that would run every 5-10 minutes would also work. I do have cron-jobs enabled, obviously, but widget caches are only generated when the widget is shown and the former cache is outdated. (This is in general as it should be, since I wouldn't want to spend resources generating widgets that might not be needed. Some caches like this one, would make more sense to try and work into being updated by a cron-job instead of a visit though)

I think it may be worth submitting if you have not already, I would hope they could factor it in asap as I would hope its not a huge job to move the code over.