I've always used Reiserfs 3.6, fast and reliable.O.k. You have read the title and I am here to tell you that I have found something out about Ubuntu and Linux in general after 1 month of scientific/practical research and implementation.
1-- EXT3 is the absolute slowest part of Ubuntu.
2-- XFS is the fastest file system. Period. This is uncontestable.
3-- Preload and Prelink do help when using EXT3, but very much so when using XFS.
If Slackware uses it, there must be a reason!