A modern TeX would probably look a lot like SILE:

http://sile-typesetter.org/

Simon's a smart guy.  It's a pretty neat project.

On Fri, Oct 4, 2019 at 9:13 AM Jon Forrest <nobozo@gmail.com> wrote:

>
> One slightly OT fact about TeX. On my 16GB, Core i7, SATA SSD
> Lenovo T430s laptop running Fedora 30, it takes ~3 seconds to run TeX on
> the ~900 page TeXBook. That's pretty fast. TeX contains all kinds of
> code to make it fit in the constraints of a 1980s computer. I wonder
> whether a redesign for a 2020 computer would be faster or slower.
>
> I suspect, but can't prove, that classic [nt]roff might also
> benefit in the same way. groff was written latter, so it might
> suffer less.
>
> Jon
>