IIS Performance Tweaking When working with IIS, make sure that you research on how to tweak the settings for better performance. Application Pools are an integral part of the Application performance, they exist to separate applications from running process and carry different privileges on the Windows System. For example, one Application Pool might have different settings to run (Process) with limited privileges some Application Pools might have System Privileges that would give priority to its process when running. This is important for performance, you want to give more thread to an Application Pool running your best Web App for speed and this is done by changing the Identity of an Application Pool to run a process under a highly privileged account on your computer or Server.