Hello Kinsie,
First of all - thanks a bunch for your mod, I love it. Breathes new life into maps.
I'm writing to ask if it would be possible in your current implementation of the code to add a toggle ON/OFF from the in-game Options menu? Particularly to get around the rare maps with huge lava seas (which you mention in Known Issues) and their respective performance tank. Or would this be impossible without restarting GZDoom? I know I could just restart GZD without loading the pk3, but the problem there is that a savefile using FancyWorld will result in a crash if loaded without FancyWorld.
Another interesting observation I made while replaying through the IWADs again - "MAP20: Gotcha!" from Doom2 lags extremely hard (~15 fps) after the room with the cyberdemon+spidermastermind fight (probably because of everything, including the roof, being lava). However, "E3M6: Mt. Erebus" from Doom does not lag that hard, even though it also has a lava sea. I noticed that MAP20 uses a different darker red lava than what E3M6 uses. I wonder why there's such a stark performance difference between the darker red lava and the yellower lava?
http://ian-albert.com/games/doom_2_maps/MAP20.jpg
http://ian-albert.com/games/doom_maps/E3M6.jpg