Mat Keep about the multi-threaded slave replication available in MySQL 5.6:
The multi-threaded slave splits processing between worker threads based on schema, allowing updates to be applied in parallel, rather than sequentially. This delivers benefits to those workloads that isolate application data using databases - e.g. multi-tenant systems deployed in cloud environments.
Original title and link: Benchmarking MySQL Replication With Multi-Threaded Slaves ( ©myNoSQL)