Consider using additional Worker Processes for Application Pool per 600MB of physical memory to add  resilience and enhance performance In IIS 6.0 and above, an application pool configuration that is supported by multiple worker processes is known as a Web garden. Creating additional worker processes creates additional w3wp.exe processes running in your operating system. For example, if you have 1.5 GB of free memory at peak use of the server, you could create two additional worker...

If you want your Index server to crawl a particular WFE, leave the default setting alone and modify the HOSTS file yourself. This way you can direct it to hit one server for some sites and another for others. The issue with the default behaviour of OOTB SharePoint feature to choose the WFE for the crawling is that it doesn't modify HOST file correctly. SharePoint set the IP address of the WFE server to crawl in HOST file, but under some circumstances it may set the wrong IP. The reason for ...