Hi There Zentz,
A load average of 6-8 for esentially a four core server, is definitely overloaded.
Especially if it holds at that level consistantly. Performance will definitely suffer at that level.
You did not mention what OS you are using because that can make a huge difference - and in your options to deal with this.
Adding RAM is usually the quickest way to bring the load averages down.
But ideally, on a four core box, you want that load average at 2 or less.
I also strongly suggest that you explore what is called "null routing" to deal with hotlinkers/freeloaders (assuming you already have sufficient htaccess protection in effect).
Null routing is where you block ip addresses from your server by country of origin. This will elimate server load from countries that don't produce income.
It has become very very common practice, for example, for commercial porn sites to block literally all of mainland China.
You can get a current and constantly updated list of IP assignments by country from
http://www.ipdeny.com.
Best regards,
Archer