The most obvious reason for the Hurd feeling slow compared to mainstream systems like GNU/Linux, is a low I/O system performance, in particular very slow hard disk access.
The reason for this slowness is lack and/or bad implementation of common optimization techniques, like scheduling reads and writes to minimize head movement; effective block caching; effective reads/writes to partial blocks; reading/writing multiple blocks at once; and read-ahead. The ext2 filesystem server might also need some optimizations at a higher logical level.
The goal of this project is to analyze the current situation, and implement/fix various optimizations, to achieve significantly better disk performance. It requires understanding the data flow through the various layers involved in disk access on the Hurd (filesystem, pager, driver), and general experience with optimizing complex systems. That said, the killing feature we are definitely missing is the read-ahead, and even a very simple implementation would bring very big performance speedups.
Here are some real testcases:
running the Git testsuite which is mostly I/O bound;
use TopGit on a non-toy repository.
Possible mentors: Samuel Thibault (youpi)
Exercise: Look through all the code involved in disk I/O, and try something easy to improve. It's quite likely though that you will find nothing obvious -- in this case, please contact us about a different exercise task.