This does not affect smoke or the falling dust clouds, only the really ugly floating bits of ???? hanging in the air.
This is just a set of very small (8x8) empty textures.
This will not improve performance at all, unless saving a very small amount of VRAM is significant on your machine (and I mean very small).
I thought there was a file like this already on Oldrim, but I could not find it, so I made it.
I made some screenshots, but the really ugly bits don't show up very well. Need to make a video, but that would take more work than making the file...