Which is the fastest stream compression for replication of two FreeNAS 11.3 on the same network?

[vafk]

I upgraded from 11.2 to 11.3 and need to backup my FreeNAS1 to FreeNAS2 and FreeNAS3 located on the same network. Pool on FreeNAS1 has lz4 compression. What is the best setting in replication tasks for stream compression (lz4, pigz, plzip) or can it be disabled since the pool is already lz4? I am a little confused because lz4 says fastest while some posts day that if pool is already lz4 the compression can be switched off.