MySQL replication slave VERY slow
Sorry, I need a 50 rep to comment, so...  Here's a couple of things to start.


Are you by chance using ZFS for your filesystem (it can throttle the disk unexpectedly)?
Are your config files (nearly) identical (with exception of replication master/slave settings)?  The config should be the same as the other slave except maybe memory buffers (sounded like the server HW was different).  https://www.percona.com/doc/percona-toolkit/2.2/pt-config-diff.html
(Run on the slave, and post) SHOW SLAVE STATUS\G
(Run on the master, and post) SHOW MASTER STATUS\G
Check the Slave Status a few times (maybe a minute apart). Are both Exec_Master_Log_Pos and Read_Master_Log_Pos (or Retrieved_Gtid_Set and Executed_Gtid_Set), moving (ideal is if they are catching up)?
Are the relay logs being stored as tables or files?


Edit
After reading Rick's post, I went back and noticed (thought at first both were SBR) your cluster that runs faster is running SBR (statement based replication), and the slow one is RBR (row based).  Rick's question about the type of queries and how many binlogs you generate in say an hour is important.

Sometimes RBR is faster, and sometimes SBR wins.  Always important to test and benchmark all scenarios.