When we set debug="true" in web.config, it will create below problems:
1) ASP.NET Request won't timeout at all
2) Batch Compilation won't happen
3) Code will not be optimized
4) More memory is used for the application at runtime
5) Scripts and images downloaded from the WebResources.axd handler are not cached
6) Source code files will be copied to Temporary ASP.NET Files folder under .NET Framework folder.
It will be hard to go and check each web application's config and change it to "false". The shortcut is go to your Production server's machine.config and add
<deployment retail="true"/> under <system.web>.
This will make debug="false" for all web applications running on your server.