High load on nagios central server


Currently I’m having 1 central server, 3 pollers and 1 database server.
178 Hosts / 2300 services to check.

Nagios version: 3.1.2
mysql version: 5.0.51a-24

The load on the central server is always 15~30. which is pretty high.
Although i have tweaked some settings. the load is not decreasing.

Check Execution Time: 0.00 sec 33.60 sec 1.361 sec
Check Latency: 0.00 sec 252.69 sec 1.189 sec
Percent State Change: 0.00% 12.37% 0.02%

Above are the figures from the nagios performance page.
Anybody has some suggestions how the deal with this ?
If you need any additional information please tell me and I’ll try to post this asap.

btw: when i check with top i see multiple checks being processed. but when i check the nagios log it only reports some checks and not all :cry: