We have a webserver that's reacting slowly. It seems that a DLLHost.exe is the problem (taking ~100% Processor). How do we tell which dll in DLLHost is causing the problem. We've seen which ones are loaded with Process Explorer, but the list is 100 DLLs long. What tool or technique can we use to isolate the problem?
There's an excellent article on debugging high CPU usage of IIS. If you follow this you should be able to create a dump file that may help in determining which DLL is causing the problem.
Once you have determined what DLL is causing the problem its then a case of trying to find out what its doing, and what's causing an issue. Quite often, at least with DLL's written for custom software its because the code is stuck in a loop.