RMMV makes use of on-the-fly loading very often. It leads to a bug when using Window_Base.drawFace() often.
It has to work this way, since it needs to account for any possible face image, but I already know for sure I'm using a single image each time, so I just load it once, and store it as a local variable. caching? preloading? something.
It helps with the frame hit when opening the menu, and solves this bug where my summoning menu wouldn't draw the faces at all.
I have a feeling I'd eventually want to do this sort of preloading/caching for every bitmap I use, because the asynchronous loading is pretty ugly.