This is about windows, and I have exactly the same issue here - CPU running at 15-20% when doing absolutely nothing with the program, simply minimised in the background.
No other software does this on my PC, and it is a fresh Windows 10 install, so it is definitely an issue with Evernote.
"That some people seem to have similar problems says nothing." That is the most staggering comment I have ever heard from someone saying they are part of "support".
Only subscribers can contact support, the rest of us are sent here. What we have received so far is "it isn't a bug as people haven't been complaining" and when people complain we get "That some people seem to have similar problems says nothing." from a guy who isn't even using the same operating system.