Strongly encourage retro devs and fans alike to read the tale of the tape in how this got better. It takes some serious stones to take Carmacks work and to actually get serious perf improvements out of it.
I seem to recall Carmack looking back at the code of Doom and going something like "if I knew then what I know now then it would be lots faster", meaning that certain algorithms were poorly chosen at the time, and that today we know of lots of tricks and improved ways to render the same thing with less work, so perhaps there are lots of people now that could improve it.
Not saying this isn't a great feat, just that things like compression also advanced in the last 30 years in both speed and efficiency, so it stands to reason that 3d engines (especially the early ones) would have certain spots you could improve upon a lot.
Not saying this isn't a great feat, just that things like compression also advanced in the last 30 years in both speed and efficiency, so it stands to reason that 3d engines (especially the early ones) would have certain spots you could improve upon a lot.