When doubling the tested file-size to 4GB, EXT4 remained in first. The positions were identical to that of the 2GB write performance, except for the Btrfs slightly outdoing XFS. NILFS2 remained the slowest.
Switching from 4GB writes to 4GB reads, the EXT4 file-system was the fastest, again. EXT3 followed in second and in a distant third was XFS. Further behind that was NILFS2 and then finally was Btrfs, which was over twice as slow as EXT4 at this IOzone test.
When testing out the 8GB write performance, to not much of a surprise, EXT4 won. The NILFS2 was the slowest file-system with a speed of 66MB/s compared to Btrfs at 78MB/s and EXT4's great finish with a speed of 99MB/s.