There were some marginal improvements with ext4, especially in boot times and when copying significant amounts of files, but perhaps not enough to overcome the . (You might be wondering if the hibernate to disk performance is improved but remember that Ubuntu hibernates to the swap partition, not the filesystem, so this is unaffected; I realized this after performing my tests, but it was borne out in my results which were virtually identical between filesystems).

Ext3

Boot from cold: 25.93 seconds

Start Firefox on a cold machine: 4.64 seconds

Start OO.org Writer on a cold machine: 7.11 seconds