Okay I have some experience reviving some old 32bit computers so here is my opinion.

Tiny core is crazy fast for old hardware. Installing that thing is like ducktaping a jet engine to a bicycle, is amazing. However it brings all the problems you can expect with ducktaping a jet engine to a bicycle. To use it without going mad you need to comfortable with linux.

On second place is Debian with lxqt. It's light, usable, the easiest to install and use. It will not blow your socks off but it will be usable. I recommend lxqt because it has better suport than lxde. For the installation I never used the graphical install only the ncurses one and in the software selection I only choose "lxqt" and "base system something".

If you want Debian but faster to boot use Devuan with OpenRC.

Another option is Alpine, that shit is light and flexible but again you need to be comfortable with Linux. I don't use it because wifi didn't work.

Void is really nice, it's an amazing project. But again I had wifi problems.

I never tried Slackware 32 but it seems like a good option. However I think it may give more headaches than other options on this list

I used arch32 and I recommend against it. The project is barely maintained I had a lot of package problems and it was really unstable.

I do not recommend using Gentoo (or LFS for that matter) for speed. The performance improvements you get from building everything from source are negligible. It's a great project to learn linux and control freaks as myself but not for performance.

Tips: Read the Arch wiki "improving performance" page. Web browser (gui) - falkon Web browser (cli) - links (I found it more "user friendly" than lynx) Video player - mvp Terminal - xterm And I forgot the rest, sorry xD