Vaal Factory Seems Unoptimised for Performance?

Generally haven't had any issues with most any other map, but I seem to consistently have dropped frames on Vaal Factory. Doing T15 (lvl 79/80) Vaal Factory maps, the textures take awhile to load (so I have to pause for a bit to let that happen upon entering the map), and even then I get several low frame counts (~15 fps) during the map where I usually don't ever dip much below 55 fps on any other map?