MySQL is using 150MB of my RAM memory when it's doing nothing.
I have a VPS with only 256 MB ram available, so what can I do to decrease its RAM usage?
There are example my.cnf files included with the MySQL packages on most distributions, on RHEL / CentOS they can be found in
my-small.cnf is designed for systems with a small memory footprint, so may be suitable for your application.
Alternatively you could follow a MySQL tuning guide on the web to find the commonly tuned memory parameters and simply decrease rather than increase the values.