30-40% CPU Usage?

Can somebody help me find a way to cut back on my the CPU usage for the server I’m using? I currently host a small site which has recently started to average anywhere from 2,000 to 2.8k viewers daily. We currently have 15 posts displayed on our front page (our account is currently suspended) about 6 plugins installed (including WP-Cache) and we cannot figure out why we are using up so much of the CPU load. Does anybody have any idea as to how else we might cut back?