The Mesa project was started in 1993 by Brian Paul, and he's still developing it! Really impressive!
Related Posts
I've started keeping a list of particularly interesting bugs and patches that I've worked on: https://github.com/Wilfred/interesting-code
The time that I once removed *a single closing paren* in Emacs is still my favourite.
Blogging about my programming language project: choosing the basic syntax!
https://www.garden-lang.org/blog/syntax.html
It's really satisfying to use a profiler for the first time on a project. I always find a big performance win with only a small code change.
It's never the code that I expected to be slow, however!