Faster performance for the new ZFSOnLinux release comes for read performance on mirrors through using the least busy device and increased IOPS performance with L2ARC through using LZ4 compression. There's also numerous bug-fixes and other minor improvements.
ZFSOnLinux 0.6.2 also has Linux 3.10 and Linux 3.11 kernel compatibility. For newer post-3.8 kernels there is laso now GRSecurity/PaX compatibility and user name-space compatibility.
More details on the new ZFSOnLinux release can be found via this forum thread.