Application Pools

IIS application pools provide a way for multiple sites to run on the same server computer but still have their own worker processes and identity. This can help to prevent an exploit on one site which enables the attacker to inject malicious code that can attack sites in different application pools.

Application pools are used for security separation. Memory leak will not bring other applications down. There are instances when an error (null pointer, buffer overflow) can bring the whole application pool down.

When each Web application starts, it loads an App. Domain into a memory. (.NET Framework instance) Depending on the complexity of all active Web applications, memory required to run all desired Web applications may grow significantly, and general guidance for the maximum number of applications sharing the same application pool may not apply.

Using separate application pools in your EPM Focused Office SharePoint Server Intranet Farm has no adverse effect on Office SharePoint Server and PS  components coexistence such as web parts