Hi Mark,
Yes, the app called The Time by Jeff Key is the same program I had as yours. I agree what we have in common are Wikipedia and The Time so I began testing with Wikipedia first and I do see that Runtime Broker was consistently in the range of 19.1-19.7MB.
It never increased beyond that.
It took me a while to reply to you as I was still in the process of analyzing whether The Time is the cause of a memory leak but now feel I have a good answer for you (and whoever runs into the same issue and reads this thread).
Here is the data that I recorded:
Why is Runtime Broker consuming too much memory? Appears to be a bad App.
10/31/2012 after removing downloaded Apps.
Runtime Broker memory consumed is 2.7-2.8MB. with Mail App actively running.
If mail app closed,then Runtime Broker memory consumed is 2.6MB with no Apps running
10/31/2012 3:06am Runtime Broker memory consumed is 3.7MB
10/31/2012 8:25am Runtime Broker memory consumed is 3.5MB
10/31/2012 8:37am after Wikipedia install Runtime Broker memory consumed is 19.3MB
10/31/2012 8:58am Runtime Broker memory consumed is 19.5MB then went to 19.1MB
11/1/2012 12:13am memory used by Runtime Broker is consistently in the range of 19.6-19.7MB
11/1/2012 12:14am installed The Time (the one created by Jeff Key). Runtime Broker memory consumed is is 19.7MB
11/1/2012 12:17am Runtime Broker memory consumed is 20.7MB
11/1/2012 12:31am Runtime Broker memory consumed is 59.3MB
As you can see, it was only after I installed The Time did Runtime Broker memory usage began to increase significantly. I'll now uninstall it and report feedback in "Store" that this is a problem.
Good luck to you and I'm glad to be of help to you and whoever else is out there.