ProJoomExperts

But there is an problem too. A lot of plugin , modules and extensions makes Joomla very heavy. So then it uses a lot of resources like CPU and Ram. And your host send you notification about it or sometimes they turn your website down.

Now there is several way to prevent this problem. I will tell you about them

First of all  ask your hosting support to tell you more about the process that is using most resources. So that you can find the extension that is creating the problem. If they tell you about any specific extension. Disable it temporarily and contact the extension developer about the issue. also remove any unnecessary modules , plugins and components ( except the default ones ). Keep your joomla website clean. If you think you will need any extension in future, just disable it for now and when you will need it , you can enable it back

Second, Check if you have any cron jobs that runs very frequently. You can check that in your control panel (cpanel). A lot of cron job can put a huge pressure on the server.

Third, Enable Joomla conservative caching and set the time according to your need. You can do it from the Global Configuration ( under system tab) . Set the cache time according to your need. If you post new information frequently decrease your cache time. If your website is static or get updated rarely increase the cache time. Believe me it will make huge difference. Because cache creates static copy of pages and delivers to the visitor without putting pressure on the cpu. 

Also you can use third party caching extensions from JED. That can help you too. When you enable caching any recent changes may not be visible on your website instantly. You can use this cache cleaner extension to instantly clean you cache.

Still if you are having high cpu usage comment on this post so that i can help you with it.