IIS 7 and Above
IIS best configuration
Re: IIS best configuration
May 14, 2020 02:15 AM|Jalpa Panchal|LINK
Application pools allow you to isolate your applications from one another, even if they are running on the same server. This way, if there is an error in one app, it won't take down other applications.
Additionally, application pools allow you to separate different apps that require different levels of security. The primary concern of using the Application pool is to isolate two different applications with different security concerns and also to avoid
crashing of applications due to worker process death.
So in opinion use, different application pools for the different sites is a batter option.
you could also limit your application pool CPU usage:
1)Open IIS Manager.
2)Expand the local server and click Application Pools.
3)Find the application pool you wish to limit and right-click on it.
4)Click Advanced Settings.
5)Under the CPU section, set "Limit (1/1000 of %)" to the amount of CPU you wish to be the maximum, multiplied by 1000. (ex: 25% would be 25000)
6)Set Limit Action to Throttle or KillW3wp.
7)Click OK to apply.
and if you want to troubleshoot the issue you could try to use the Debug Diagnostics tool.