How to check the time taken by a request for my web application.

One of the asp.net application hosted in prod  is running with  debug='True' (in Web.Config).
As we know it makes the application slow so I  asked team to set it to False but they want to know how Debug='True' makes our application slow.
Is there any tool to capture the  time taken by our application for each request with debug='True' and Debug='False'