Btrfs File-System For Old Computers?
The only Btrfs mount option that allowed the Btrfs file-system to perform close to the speed of the EXT4 file-system was when disabling barriers for Btrfs. However, not using device barriers is a hazard as you can end up with a corrupted disk if your system loses power during writes. While disabling barriers can increase the performance, the risk is not generally worth it unless you are confident in your battery system regarding power loss or other crashes.
Btrfs was also slower than EXT4 with the SQLite database and only when disabling barriers was it faster than the evolutionary EXT4. Interestingly, the auto-defrag option did not help the SQLite workload.
Btrfs is at least faster than EXT4 when it comes to the PostMark mail server benchmark. Btrfs with its default mount options was faster than EXT4 by over 10%. The mount options that were of the most benefit to EXT4 were compress=lzo (LZO compression) and autodefrag. Other options like nodatasum (no checksum data) and nodatacow (no copy-on-write data) were also of modest benefits.