Public Hotfix Patch Available for VS 2005 F5 Debugging Performance Issue with ASP.NET

Over the last year we've seen several people report having performance problems when using F5 to run/debug ASP.NET 2.0 applications using Visual Studio 2005.  The problem in theses cases typically wasn't with building the project, but rather that it sometimes took the debugger a really long time to hit the first breakpoint once it attached to the application (45+ seconds and longer sometimes).

We recently posted a public hotfix patch that you can download and apply to fix this issue.  You can download the hotfix immediately here.  You can read more about it in this KB article here.

Background on the Issue

The particular bug fixed in this hotfix was surprisingly difficult to track down.  The slowdown issue occurred when breakpoints were set in multiple source files in the same project that had the same short file names (for example: two default.aspx.cs files) and which were organized in a certain directory structure pattern on disk.  The patch fixes this issue and should prevent the debugger from pausing when trying to load the web project's assembly symbols in this case.

For Technical Support with this Patch

If you have any problems installing the patch or find that you still see issues after you install it, you'll want to contact Microsoft product support for assistance and they'll help debug it further.  Calls to Microsoft Product Support are free if they are related to a product bug (either a QFE HotFix request or a product bug you are running into).  You can find details on how to contact Microsoft product support on this page (it allows you to lookup the local phone number to use by country).

Other Hotfix Patches

I've posted in the past about other ASP.NET and VS related hotfix patches that can be publicly downloaded.  Here are a few pointers to these posts:

More Performance and Tip/Tricks/Tutorial Posts

Make sure to check out my Tip/Trick: Optimizing ASP.NET 2.0 Web Project Build Performance with VS 2005 post if you have build performance issues with VS 2005.

Please visit and bookmark my ASP.NET 2.0 Tips, Tricks, Recipes, and Gotchas page for a good listing of some of my previous ASP.NET and Visual Studio posts and tutorials.

Hope this helps,



  • Hi Rob,

    >>>>>> I assume this is fixed in Visual Studio 2008?

    Yes - this is also fixed in VS 2008.



  • Hi Vikram,

    >>>>>> But I think this should have been done in the big SP 1 that came for VS 2005.

    Unfortunately this particular issue wasn't understood/known in the SP1 timeframe (and might have actually gotten worse in that timeframe due to another SP1 fix). It was surprisingly difficult to track down and get a consistent repro.

    >>>>>> Is the problem also persistent in VS 2008 beta 2? If yes I hope it will be fixed in the release version.

    It is fixed for VS 2008 (I believe already in Beta2)

    >>>>>>> Also Is it advisable to use this hot fix, If I am particularly not facing this issue very much.

    If you aren't running into the issue then we don't recommend installing the hotfix (this is true for any hotfix we ship).

    Hope this helps,


  • Please Help Scott.

    Question regarding VS 2005 and deploy web sites. I have encounter an issue regarding the compiliation and deployment of a website when the solution is stored on a Mapped Drive (NETBIOS error). I have seen many posts online surrounding an issue but could never resolve it. I have many tools at my dispossal and have been given the green light by management to purchase anything that can help fix this issue, do you know of any solutions? Please help.

  • Hi Scott,

    Thanks for this great article. I just want to get your opinion in adding another level of security on the data itself for the same role. I'm working on a retail company that has several stores, and there are roles that can access a single store, certain stores or all stores. What do you think would be the logical solution for this issue. I'm thinking of adding another table with all the user id's and the stores attached to the id.

    Thanks a lot.


  • Hi Ivo,

    >>>>>> It appears since I applied the Hotfix, when I get a compiler error, Visual Studio won't display the file it is in anymore. Does this relate to the hotfix or is it a setting in Visual Studio I overlooked?

    I'm not sure what that issue is. Can you send me email ( with more details about it?



  • Hi jmunsch,

    If you can send me an email ( we can have someone take a look and figure out what the problem is. It definitely sounds like something is going wrong there.



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