Increase xinetd priority

Hello. I've a RHEL server running a database service "ctsql" wich is under
xinted service. This database service is the main task of this server.
I want that this service has the highest priority. I have configured this
service on /etc/xinetd.d in a new "ctsql" file.
I have configured xinetd.conf: instances = 600 cps = 600 30 to allow
multiple connection (more than 60).
It works good but I have testing cpu load, and I have seen it's always under
20-30% of load (in fact, under 10%). But, sometimes, client-applications
runs SQL querys slowly but the server is not at 100% to serve data as fast
as possible.
I think It could be because this service hasn't high priority. I don't know.
How can I increase the priority of this service? should I include "nice" on
ctsql file? How can I do it?

Thanks.