Performance in debug mode (F5) vs. no debugging (Ctrl+F5)

Question

Hope you guys can help me with this problem: My C# app performs almost 3x as fast when I run it in Debug mode (F5 in Visual Studio 2003) as when I run it without debugging (Ctrl+F5). I would think that running in Debug mode would decrease the performance, but in this case it is actually faster. In any case, the difference in performance numbers is appalling to me. The app is a server stress tool that spawns multiple threads to simulate multiple users hitting the server. In Debug mode, it stresses the server to 100%. Running without debugging, the server CPU counter can only get to about 35% at the highest. Any help would be greatly appreciated! Thanks!!

robin 0 · Answer

In your situation it means that your application really stresses server for only 35%... other 65% that are stressed in Debug mode are stressed not with your app but with debug shell and debugger itself. If you're creating some kind of server tester for extreme situations - I recommend you to add to your app some module of diagnostic of CPU usage. So that your app works till CPU usage got 100% and then may be gives a report about at which condition CPU becomes 100% busy.... If you are using some predefined settings (number of threads etc.) - then it means that your server is much more stronger that modelled situation and you probably need to increase resource usage of your threads...