Reverse proxies (Varnish, Squid or Nginx) are designed to quickly serve content (e.g. HTML pages and images) using as little of the CPU as possible. You can therefore minimize the infrastructure needed by avoiding unnecessarily accessing the application server.

You can use either single (‘) or double (“) quotes to declare a character string in PHP. Double quotes allow the developer to insert variables which will be substituted when run.
But if the character string has no variables, use single quotes instead. This stops the PHP from looking for variables to substitute, reducing CPU usage.