Site shut Down because of cpu usage - nop 2.3

So i recieved a letter from my host today that they have shut it down because of to much cpu usage.

So currently out of business :(

I run nop 2.3, have about 50 items In the store and about 50 visits a Day... How can this be? ...and what can i do to correct it?

Need help asap please!

Cheers

I would pick a more competent host.  How can they shut down you're site for too much CPU usage?  NOP, which is really just MVC, is very efficient.  Did they provide you with any server logging information to backup their claims?  If not, then ask them for it.  If they did, then please show us your logs.  If they won't provide it, then demand that they turn your site back on.