I think by default event graphics are drawn slightly off screen since events normally update even if they are "near the screen", but tiles and a few other things do not get drawn by default. This is also why zoom plugins usually struggle with zooming out, as they need to draw more of the map or you would just see the black void.
I do have it on my to-do list to see if I can optimize how pictures work in RPG Maker at all, now that they allow up to 500 pictures some people have ran into lag with them.
If you run into any lag you can post here and we can troubleshoot the cause / I can see if I can update this plugin to address that lag source.