Comment 12 for bug 646638

Can you give some metrics with the following commands:
$ echo 3 | sudo tee /proc/sys/vm/drop_caches; sudo dpkg -i /var/cache/apt/archives/ubuntu-docs_10.04.3_all.deb |ts
$ echo 3 | sudo tee /proc/sys/vm/drop_caches; sudo dpkg -i /var/cache/apt/archives/openoffice.org-common_1%3a3.2.1-6ubuntu1~10.04.1_all.deb |ts

(ts is in moreutils)

Can you try with ext3 instead of ext4 ?