Optimizing mySQL performance on MacOS X
By default, MySQL service on Mac OS X Server dynamically changes the priorities of its worker threads. On Mac OS X Server this leads to reduced MySQL performance under increasing loads, so you may consider overriding MySQL's default thread prioritization by using the skip-thread-priority option.
You can pass "--skip-thread-priority" as an argument to mysqld or mysqld_safe, if you are starting mysql manually or with a custom script, or
You can edit the MySQL configuration file /etc/my.cnf (or create one if it does not already exist), ensuring that the [mysqld] section contains the skip-thread-priority option. This is the recommended method if you are using the MySQL Manager application to manage the pre-installed version of MySQL on Mac OS X Server.