The most obvious reason for the Hurd feeling slow compared to mainstream systems like GNU/Linux, is very slow harddisk access.
The reason for this slowness is lack and/or bad implementation of common optimisation techniques, like scheduling reads and writes to minimalize 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 optimisations at a higher logical level.
The goal of this project is to analyze the current situation, and implement/fix various optimisations, to achieve significantly better disk performance. It requires understanding the data flow through the various layers involved in disk acces on the Hurd (filesystem, pager, driver), and general experience with optimising 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.
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.