[devnonymous]

My recommendation would be to actually measure the performance of the servers, isolate and address any possible bottle-necks in the application side of things[1] before attempting to solve the problem using load-balancing. If, for instance the problem is with your DB or with the communication with the DB, splitting the incoming traffic really won't help much and depending on the actual case, might worsen the situation.

At the very least, get the numbers for:

  1. Response time for a single static file request
  2. Response time for a non-db php request (eg: phpinfo() )
  3. Response time from the application for a non-db request
  4. Response time from the application with a db request
  5. .... with/without plugins ...you get the idea

This will tell you where you need to concentrate your performance improvement efforts on.

Also, look at solutions that are easy to implement and offer immense benefit for very low effort like server-side caching (eg:https://github.com/BenjaminAdams/wp-redis-cache / http://www.jimwestergren.com/wordpress-with-redis-as-a-front... )

cheers,

[1] Your statement that Client uses some WP Plugins to generate content, this hangs the server every time as CPU consumption is a lot. is an alert.