Is there a runtime comparison of the shaders needed? Seems like you might have to do a lot of texture sampling if you have to walk the ray through the data but maybe there's a trick?

MSDF is pretty much just the target texel in question plus the surrounding samples in a way the GPU can do entirely upfront before the math starts. (M)SDF glyphs also play nicely with mip mapping and I would think this Slug algorithm needs uncompressed data. Maybe that doesn't matter because you just don't scale the data ever?

Slug doesn't use "bitmap" font data but more like parameter lookup tables in storage buffers, pre-processed from TTF files. The lookup data can of course also live in textures (so that it works in WebGL), but using those textures as "poor-man's storage buffers", e.g. fetching the data directly without filtering.

The pixel shader is indeed quite complex compared to SDF:

https://github.com/floooh/sokol-samples/blob/8afa83928ce1870...