With all of these solutions, the key to performance is cache control. LiteSpeed/OpenLiteSpeed can handle incredible traffic volumes when serving from cache but once you hit the PHP application and talk to the database that will consume CPU and memory as a multiple of the number of concurrent requests you are handling.
One upcoming feature in Enhance (not yet roadmapped) is the ability to modify the default web server ports from 443/80 to a custom port. This would enable you to use Nginx or another caching proxy in front of Apache (or even LiteSpeed/OpenLiteSpeed).
We are also adding support for Nginx as the primary web server.
In time we may also be able to develop caching solutions for Apache which can be configured and controlled directly from the panel.