Reduce your server's resource usage by moving MySQL temporary directory to tmpfs
For sites that have lots of slow queries, disk access is often the bottleneck. For these slow queries, MySQL writes temporary tables to disk, populates them with intermediate results, then query them again for the final result.
We all know that the disk is the slowest part in a computer, because it is limited by being mechanical, rather than electronic. One way of mitigating this is to tell MySQL to use memory rather than disk for temporary tables.