13.408 Loading mod DeadlockStackingForSchallAlienLoot 0.0.2 (data.lua)
13.409 Script @deadlock-beltboxes-loaders/prototypes/shared.lua:17: DBL: Warning: creating layered stack icon (alien-artifact), this is 4x more rendering effort than a custom icon!
13.409 Script @deadlock-beltboxes-loaders/prototypes/shared.lua:17: DBL: Warning: creating layered stack icon (alien-ore-1), this is 4x more rendering effort than a custom icon!
13.410 Script @deadlock-beltboxes-loaders/prototypes/shared.lua:17: DBL: Warning: creating layered stack icon (alien-ore-2), this is 4x more rendering effort than a custom icon!
13.410 Script @deadlock-beltboxes-loaders/prototypes/shared.lua:17: DBL: Warning: creating layered stack icon (alien-ore-3), this is 4x more rendering effort than a custom icon!

13.745 Loading mod DeadlockStackingForTheDeadBurn 0.1.0 (data.lua)
13.746 Script @deadlock-beltboxes-loaders/prototypes/shared.lua:17: DBL: Warning: creating layered stack icon (monster-body-small), this is 4x more rendering effort than a custom icon!
13.747 Script @deadlock-beltboxes-loaders/prototypes/shared.lua:17: DBL: Warning: creating layered stack icon (monster-body-medium), this is 4x more rendering effort than a custom icon!
13.747 Script @deadlock-beltboxes-loaders/prototypes/shared.lua:17: DBL: Warning: creating layered stack icon (monster-body-big), this is 4x more rendering effort than a custom icon!
13.747 Script @deadlock-beltboxes-loaders/prototypes/shared.lua:17: DBL: Warning: creating layered stack icon (monster-body-behemoth), this is 4x more rendering effort than a custom icon!

It does that a lot. But I have now written some python code to make my own stacked graphics and will update this mod in next 24 hrs or so.

BTW. Any plans to upgrade your graphics for icons to use 64x64 ? Most of the in game icons were updated in 0.18

I am working on the graphics. Aliens is easier but for the rest I need to find something on internet.

This mod is for "Schall Alien Loot" I will update your Necromancer one next

Great!

As for the graphics comment, I just posted this: https://mods.factorio.com/mod/necromant/discussion/5e4d689f008123000bf59201