We are facing high CPU : More than 90% for higher concurrency load test on all 3 webserver instances . All these webservers pointing to same Publisher instance.
Can Dispatcher cause high CPU ? Any tuning configurations?
That's an odd topology. Typically you would map a single Dispatcher to a single AEM Publish 1:1.
Unusual to point 3 Dispatcher's at a single Publish...
Adding to Marc's point, you might need to optimize caching. Check  for more details.
 Optimizing the Dispatcher cache
Optimizing AEM Site Caches
High CPU usage can have many root causes. First of all, does the webserver/dispatcher cause this high CPU usage or is another process causing it?
What operating system is this? What hardware? What disks are used to store the dispatcher cache?