Snap to Intersection can cause serious speed issues due to the millions of possible intersections in complicated files. The solution to be able to use this invaluable feature is to (with key shortcuts cmd+I and cmd+R) Isolate objects to be snapped and then Reveal all when the operation is complete.
Justin - I always save files using Open Fast, I autosave large files often and I don't like the delays while FZ is saving. Is three notches over working well for you? I will try it for awhile to see how it goes. What was ADS' reasoning for that position on the slider?