Hey
I am a senior web developer at a reputable company down here in south africa, We are one of the top responsive development companies. Being in a third world market, we have to deal with substandard servers and limited processing resources. This means that we have to build sites which dont kill the server.
All the software (plugins) you speak of I personally have worked with and they have never thrown cpu spikes like you are describing.
- I have worked with woocommerce and their developers are topgun when it comes to performance.
I think that your bottle neck may be in the theme, or misconfigured wordpress install (rewrites might not be correct, taking the server longer to resolve them) You could have endless loops from bad php code.
I have found that even TotalCache can actually hinder performance in some regards. If you have cpanel access then i can take a look at the php prcesses that are running, look at the database structure and make sure that it is optimal. Look at how man database queries the site is running. I have seen sites with 300 database queries, taking up to 5 seconds to just respond to a browser request.
Some Questions:
- where did you buy the theme?
- have you checked your .htaccess file to ensure memory limits and cpu cycles are set correctly?
- can i get a full list of plugins installed?
Message me with more details and we can take a look at where the issue is.