It won't use much cpu, it may be server is already overloaded causing the problem. How much bandwidth you use per month ?

Try enabling cache in admin area, so cpu usage will be reduced. Again it is upto the web host, some offer too much for nothing, that type of hosts can't host large sites. Bandwidth and cpu usage always cost... even if your host offer you unlimited everything, that is just to get customers, not every customer have video sites, so they can keep 99% of customers with out problem.