The best way to improve performance would be to take inetd out of the picture. But if you really, really have to use inetd, here are some ideas:
- Renice inetd to a negative priority.
- Turn down / off inetd logging
- Log to a faster disc / raid.
Another possibility is that your service is processing one request or a small number of requests, and then shutting down. If that's the case, then under load inetd will consume a lot of time relaunching your service. So you want to avoid that scenario.
A final possibility is that problem you are seeing is caused by server processes not terminating correctly, and hanging around using up kernel resources. In the worst case, they may be even spinning. It would be worth using your system's monitoring tools to see what is actually happening when your system is running slowly.