With the FS-Mark test using 1,000 files of 1MB size, Btrfs was slightly faster than EXT4, but even more so once enabling the zlib compression support.
When running the same FS-Mark test but with no sync/fsync being forced, Btrfs was even faster.
Lastly, with PostMark, we have Btrfs beating out EXT4, but when enabling compression in this test it has actually led to a drop in performance.
The performance of Btrfs has certainly improved a great deal since it was first introduced in the mainline kernel back with the Linux 2.6.29 release in early 2009. Today's tests show that even with old hardware both when it comes to the processor and disk drive that even still Btrfs manages to perform well both with its default mount options and then again when taking advantage of the transparent compression support. Beyond the quantitative disk results, Btrfs also provides other advantages like with the system rollback support as being worked on in Fedora and solid state drive (SSD) optimizations. We are also exploring Btrfs in other ways at Phoronix to tie it into Phoromatic for some rather unique and interesting test capabilities.
It is good to see Canonical now pushing the Btrfs installation support into Ubuntu 10.10 after it has been available as an option in Fedora for more than a year now and is even the default file-system with MeeGo. For those interested in trying out this file-system, we certainly would recommend it and we look forward to its continued adoption.