I just made some experiments and stumbled across this:
If you uncheck Real time and Crossfade in a compiled sound grid you can run as much Sounds as you like without getting out of realtime because the selected sound is precompiled and loaded on demand. So there really is only a single Sound loaded and playing at a time. Also there is a short break when switching Sounds. Of course the MultiGrid is waaaay more flexible in terms of mixing and routing Sounds. However, sometimes you wouldn't mind all of that because you only want to switch between a set of Sounds (similar to having just a single track in the MultiGrid). In this case the compiled sound grid performs better. As I am always having trouble loading all my spectral modifiers in one MultiGrid this is a valuable option for me.
I know this might be technically impossible, but maybe there is a way to make an option in the MultiGrid to precompile the Sounds in a track and turn Real time off? I wouldn't mind the short break when switching sounds on that one track; I could put all my modifiers there and wouldn't need to worry about getting out of real time. Then I can still use the other tracks for reverbs, delays etc.
I guess I'm asking for the jack of all trades (or the wool making milk giving eggpig as we tend to say in Austria 
)