MariaDB Optimization for MySQL Users
MariaDB contains many new options and optimizations which, for compatibility or other reasons, are not enabled in the default install. Enabling them helps you gain extra performance from the same hardware when upgrading from MySQL to MariaDB. This article contains information on options and settings which you should enable, or at least look in to, when making the switch.
If you are using a log of on-disk temporary tables, increase the above to as much as you can afford. See Aria Storage Engine for more details.
Threadpool is a great way to increase performance in situations where queries are relatively short and the load is CPU bound (e.g. OLTP workloads). To enable it, add the above to your my.cnf file. See Threadpool in 5.5 for more information.