EXT4 & Btrfs Regressions In Linux 2.6.36 Written by Michael Larabel in Software on 8 September 2010 at 04:00 AM EDT. Page 1 of 3. 21 Comments. Recently when benchmarking the Btrfs and EXT4 file-systems we were left surprised that the performance of the next-generation Btrfs file-system had regressed against EXT4 to the point where the evolutionary file-system is measurably faster in a greater numb