With FS-Mark when testing 1000 files of 1MB size, NILFS2 was the fastest followed by JFS, ReiserFS, and then EXT4. Btrfs was the slowest while EXT4 was in front of that. This was for the HDD. Under the SSD, JFS was the fastest followed by NILFS2. EXT4 and Btrfs were again much slower.
When running FS-Mark again but with disabling sync/fsync, EXT4 and Btrfs popped ahead as the fastest file-systems for both the HDD and SSD.
Lastly, with AIO-Stress, the Btrfs file-system was the fastest with random writes. NILFS2 came in second, but EXT4 pulled in first place. XFS came in last.
That's a look at how the various mainline file-systems are performing in their default configurations using the very latest Linux kernel with both an HDD and SSD. Obviously each of these file-systems can be tuned with different options too, such as enhancing the Btrfs performance by enabling the space cache or using on-disk compression. There's also other features to consider when choosing the file-system, such as their features and reliability, beyond just the "out of the box" performance, but these results are now out there for those interested. The results can be further analyzed on OpenBenchmarking.org.