At the popular IOzone disk test, when it came to measuring the 2GB write performance, Btrfs failed to take the lead again. XFS was the fastest while the EXT4 file-system was immediately behind that at 86MB/s, but Btrfs was at 67MB/s and right behind that was the EXT3 file-system at 65MB/s.
When doubling the write size to 4GB, EXT4 remained in front at 81MB/s while Btrfs had dropped to 61MB/s. The XFS file-system ran at 76MB/s in this test.
Btrfs finally came out ahead of EXT4 when looking at the 4GB read performance with IOzone, but it was by a very slim margin. Btrfs had sustained an average read speed of 68MB/s while the EXT4 file-system was at 66MB/s. The EXT3 file-system was back at just under 50MB/s. XFS actually won this test with an impressive 79MB/s.