Processor overload

[diana13]

Does anybody ever have problems with processor and apache processes overload while using prestashop? From time to time, my server administrator said that, when I try to load my site and it doesn't, it remains on waiting. But in the meanwhile, my site is functioning very well.
It's not server problems, since I have several sites (not on presta) on my vps that are still functioning while my prestashop site has problems.
I wonder what can I do to fix this, if is something to fix.