I didn't notice these responses earlier (I thought I was set up for notifications), anyway, I decided to dynamically adjust the interval based on how long it was taking between calls to the slot and that's been working pretty well. I'm definitely doing some heavy processing in my slot that can bog down the program and sometimes (when drawing a dynamic heat map, for instance) it just can't keep up, but most of the time, it just has to decrease the interval a little bit.

I'm looking at this article that hoffen suggested now, it looks interesting, thanks. Maybe I can improve my timing in a way that's less of a hack!