PHP needs an opcache because its standard behaviour is to discard all state after each request - including all compiled bytecode - kind of emulating the CGI mod

PHP needs an opcache because its standard behaviour is to discard all state after each request - including all compiled bytecode - kind of emulating the CGI model. Ruby web apps on the other hand tend to be run in a loop - the script never exits after a request, it just goes back to the top of the loop to accept the next request to serve. e.g. https://github.com/rack/rack/blob/master/lib/rack/handler/fastcgi.rb#L27 https://github.com/rack/rack/blob/master/lib/rack/handler/fa... FCGI.each { |request| serve request, app } It's nice because it completely decouples your app's startup time from request processing time, so you can do expensive setup stuff up-front without slowing down each request. The disadvantage to that is there's not much pressure to keep startup time low, since it's only happening once.