If you haven't an huge traffic, the server load with EE should be around 1% 
But with cloudflare, you can use the pages rules to cache as much as possible the assets.
Use a page rule like
http://yourdomain.com/wp-content/* with cache level -> cache everything browser TTL -> 1 month or more
And wait few hours, each visitors will create the cloudflare cache
Edit : you could also try Linode which is faster than DO