Read free replication avoids unnecessary row reads on the replication slave when executing write, update, or delete events. This can significantly increase the throughput of a replication slave that was previously I/O bound.

The feature is described here:
https://github.com/Tokutek/tokudb-engine/wiki/Read-Free-Replication-with-TokuDB

The benefit is described here:
http://www.tokutek.com/2014/09/tokudb-v7-5-read-free-replication-the-benchmark/

A patch for MariaDB 10.0.15:
https://github.com/Tokutek/mariadb-10.0/commit/9992195def7e739b4034902b478ee1b448b0e21a