You are doing very well for memory. Maybe more of that should be used for caching php. I've no experience with lightspeed php but it's meant to be fast.
I'm guessing your site is
http://www.whitbyseaanglers.co.uk, it's very graphics heavy and you must have a lot of visitors with your bandwidth usage. Is your site actually slow? It seems very fast to me. If speed isn't a problem I would not worry about your CPU usage, you have 8 cores, worry when it gets to 800%.
BTW I used to mail order kippers from Whitby. Best in the world.

Plus you have that whole Dracula thing going on.

EDIT: I see from your forums that your site is really very busy yet it seems fast and responsive. Really don't worry about the CPU usage.