Reiser4 Benchmarked On Linux 3.5 Against EXT4, Btrfs, XFS, ReiserFS
With the Dbench test profile, ReiserFS and Reiser4 were the noticeable last place finishers for this disk benchmark out of the Samba project. EXT4 was the clear winner.
The IOzone read performance with different block sizes had Reiser4 performing close to EXT4.
The write results weren't too interesting out of IOzone.