What is your Operating System?
Which version of Internet Security is installed?
What hardware are you using (how many cores/CPU)?
What programs are running? Dose any program extensive I/O operations (e.g. accessing a large number of files or processes)?
Do you see times of lower system load? What programs do not run then?
BTW: On my system, processes can produce a maximum system load of "only" 25%. But the computer also has 4 cores.