Feb 21, 2015 01:36 AM|Angie xu - MSFT|LINK
For performance reasons, do I need to create different Virtual Directory and different Application Pool (AppPool_B) for Images folder.
If you want to improve the IIS performance, what I am thinking is that you can enable cache in IIS to speed performance.
Internet Information Services (IIS) includes an output cache feature that can cache dynamic PHP content (or output from your Microsoft ASP.NET or classic ASP, or other dynamic pages) in memory. This can yield enormous performance improvements.
IIS automatically caches static content (such as HTML pages, images, and style sheets), since these types of content do not change from request to request. IIS also detects changes to the files when you make updates, and IIS flushes the cache as needed.
Configure IIS 7 Output Caching