I just came across this lovely writeup of a particularly annoying bug I helped squash in Ubuntu 12.04. The bug caused applications like evince and eog to load incredibly slowly, taking almost a full minute to open a PDF. It turned out to have a relatively banal cause — an initialization procedure didn’t immediately signal its failure and instead the library would wait a full 5 seconds for the initialization to finish before giving up.
Thanks for the writeup, Emanuele Rocca. I think this shows the power of open source software. An obscure bug affecting only a handful of people can still get fixed, even without much help from the original developers.