100% CPU usage

[eluser]Unknown[/eluser]
My configuration is that I have three servers: srever 1 is running the web server, srever 2 is running the mysql and server 3 is running an application server.

When I run a load test the CPU on the web server goes to 100% usage during the load test. I also run the default code igniter page with no database access.

Is there something that I can do on code igniter to prevent the 100% cpu usage.

Any help will much appreciated.