I Installed W3tc and doen few test with around 10k Hit on loader.io
My Server config 5$ DO VPS 1gb 1 cpu an 25gb Storage using php5 forget to add --php7 while installation lol
Hi Did a test with W3tc With Preload It Can handle 10 k User Like Chram http://bit.ly/2JvP8oJ and
I disable Preload Option and Purge The cache It can Handle it like a boss although There were Php Process But i can Handle 10k http://bit.ly/2Kge9W1
I Dont know why its not Bypassing The Php but still its better to use W3tc for static site rather than Fastcgi with Memcache on a Server with 1GB Ram
I tried fastcgi cache with memcache with DB and Object cache enabled as soon as 200 client Hit Your page Your server going To crash because of less ram
will do More with wp Super cache and cache enabler