asp.net-mvc symbols - Visual Studio debugging/loading very slow




to attach (25)

In my case it was

Tools/Options/Debugging/General/Enable JavaScript debugging for ASP.NET (Chrome and IE)

Once I unchecked this, my debug start went from 45-60 seconds down to 0-5 seconds.

I'm at wits end. Visual Studio is typically painfully slow to debug or just plain load ("start without debugging") my ASP.NET MVC sites. Not always: at first, the projects will load nice and fast, but once they load slow, they'll always load slow after that. I could be waiting 1-2 minutes or more.

My setup:

I'm using Visual Studio 2012 Express, currently, but I've had the same problem in Visual Studio 2010 Express as well. My solution is stored on a network drive; specifically, it's My Documents redirected to a network drive, if it matters. (It shouldn't. There are times where my site loads very fast under this setup.)

I load in Internet Explorer 9 usually, but the same problem happens in Firefox.

This can happen in any ASP.NET MVC project I work on, and it seems to revolve around having DisplayTemplates, which all my ASP.NET MVC projects do. And it's all C# and Razor, if that mattered.

Symptoms:

The system will load my symbols hundreds of times. Basically, the following, but there are at least 300 such rows, each with ever-so-slightly different DLL files for the same CSHTMLs:

'iisexpress.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\b63f8236\6775085d\App_Web_contact.cshtml.22013bb9.xighmhow.dll', Symbols loaded.
'iisexpress.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\b63f8236\6775085d\App_Web_contact.cshtml.22013bb9.cv5hktkf.dll', Symbols loaded.
'iisexpress.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\b63f8236\6775085d\App_Web_statuscode.cshtml.22013bb9.1o77hs8i.dll', Symbols loaded.
'iisexpress.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\b63f8236\6775085d\App_Web_statuscode.cshtml.22013bb9.jja-77mw.dll', Symbols loaded.
'iisexpress.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\b63f8236\6775085d\App_Web_location.cshtml.22013bb9.l_e9ev_s.dll', Symbols loaded.
'iisexpress.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\b63f8236\6775085d\App_Web_location.cshtml.22013bb9.b4n59gom.dll', Symbols loaded.

In the above, I've got three DisplayTemplates: "Contact", "Location", and "StatusCode". It appears that IIS is loading symbols twice for each time the displaytemplate gets called. Thus, if I'm displaying a table of 100 entries that calls all three of these displaytemplates, it's 600 separate symbols loaded.

This isn't a fast operation either. Looking in the log files that IIS generates, it takes about 200 ms for each symbol to load. Thus, super-long delays.

What I've Tried:

  • Debug or Release version, it doesn't matter.
  • Putting my project on a full IIS implementation on a web server runs it super fast with no problems.
  • Cassini, IIS Express 7.5, and IIS Express 8.0 all have the problem.
  • Delete All Breakpoints does nothing.
  • Clean Solution, or deleting the .suo also do nothing.
  • If I repair IIS Express, or delete the My Docs\IISExpress folder, or repair/reinstall Visual Studio → the issue MAY go away, but only for a while, before it comes right back.

Any advice at all is appreciated.

To answer more questions, yes my machine definitely has the horsepower. The infuriating thing is that the same project, with NOTHING altered, can load very very quickly sometimes, typically after I repair IIS Express and delete the My Docs\IISExpress folder. Eventually "something" happens and it's down to 2 minutes to load again. What I'm working on is not a complicated project. No external libraries or dependencies, and my VS.NET has no addons what-so-ever.

Of note, this machine has Symantec Endpoint Protection, which has a history of causing havoc. But disabling it outright (it's good to be an administrator) did not fix the problem.

I have a theory at this point. I'm thinking this is all because I'm working off a redirected folder off a network share. While the debugger was going through its hundreds of "loaded symbols" lines, I paused to see what it was doing. It was in my code, loading the DisplayTemplate I had. Stepping into the template output this:

Step into: Stepping over non-user code 'System.Threading.WaitHandle.InternalWaitOne'
Step into: Stepping over non-user code 'System.Threading.WaitHandle.WaitOne'
Step into: Stepping over non-user code 'System.CodeDom.Compiler.Executor.ExecWaitWithCaptureUnimpersonated'
Step into: Stepping over non-user code 'System.CodeDom.Compiler.Executor.ExecWaitWithCapture'
Step into: Stepping over non-user code 'Microsoft.CSharp.CSharpCodeGenerator.FromFileBatch'
Step into: Stepping over non-user code 'Microsoft.CSharp.CSharpCodeGenerator.System.CodeDom.Compiler.ICodeCompiler.CompileAssemblyFromFileBatch'
Step into: Stepping over non-user code 'System.Web.Compilation.AssemblyBuilder.Compile'
'iisexpress.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\b63f8236\6775085d\App_Web_statuscode.cshtml.22013bb9.bciuyg14.dll', Symbols loaded.
Step into: Stepping over non-user code 'System.Web.Compilation.BuildManager.CompileWebFile'
Step into: Stepping over non-user code 'System.Web.Compilation.BuildManager.GetVPathBuildResultInternal'
Step into: Stepping over non-user code 'System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert'
Step into: Stepping over non-user code 'System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory'
Step into: Stepping over non-user code 'System.Web.Mvc.BuildManagerWrapper.System.Web.Mvc.IBuildManager.FileExists'
Step into: Stepping over non-user code 'System.Web.Mvc.VirtualPathProviderViewEngine.GetPathFromGeneralName'
Step into: Stepping over non-user code 'System.Web.Mvc.VirtualPathProviderViewEngine.FindPartialView'
Step into: Stepping over non-user code 'System.Web.Mvc.ViewEngineCollection.Find'
Step into: Stepping over non-user code 'System.Web.Mvc.ViewEngineCollection.FindPartialView'
Step into: Stepping over non-user code 'System.Web.Mvc.Html.TemplateHelpers.ActionCacheViewItem.Execute'
'iisexpress.exe' (Managed (v4.0.30319)): Loaded 'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root\b63f8236\6775085d\App_Web_statuscode.cshtml.22013bb9.kwj3uqan.dll', Symbols loaded.
Step into: Stepping over non-user code 'System.RuntimeType.CreateInstanceSlow'
Step into: Stepping over non-user code 'System.Web.Mvc.DependencyResolver.DefaultDependencyResolver.GetService'
Step into: Stepping over non-user code 'System.Web.Mvc.BuildManagerViewEngine.DefaultViewPageActivator.Create'
Step into: Stepping over non-user code 'System.Web.Mvc.BuildManagerCompiledView.Render'

It looks like Visual Studio is recompiling my displaytemplate every time it's called, which is again, hundreds of times. My theory is that Visual Studio compiles the file, saves it to the network share, the network share then somehow stamps a new time on it, and Visual Studio then thinks the file has changed and thus Visual Studio recompiles it yet again. Only a theory though; I really have no clue.

For one, apparently I have offline files on (this is a desktop computer in an office; I couldn't care less). I'm going to disable, reboot and retry tomorrow.

Plus, moving my project, as is, to the local C: fixes it. It loads very quickly. But this is not ideal in a work environment. I lose Previous Versions, my code isn't backed up at all unless I manually copy it, and it's no longer shared with anyone.

I can make do with copying it back and forth from C to the network share, if it comes to it. It's much more annoying to wait two minutes for every page load.


For me it was IE 9.08.8112.16241. As soon as I used Firefox or Chrome there was no sluggish debugging with F10 or F11. I do not know what the problem with IE is but I officially despise using it for testing now.

Update: I have turned off all IE program add-ons and it is back to full speed. Turning them on one at a time revealed that LastPass (in my case) was the culprit. I guess I do not get to blame MS after all.


A quick and easy solution for those who don't have much deviation from default VS settings.

Tools-->Import and Export Settings-->Yes, save my current settings-->Visual C#

I am sure the above solution would work with other default settings too. In my case something messed up with my symbol loading settings but I could not fix it even though I tried quite a few of the suggested solutions.


Turning off intelliTrace fixed this for me.

In Visual Studio, Tools -> Options -> IntelliTrace

Then, uncheck the checkbox for "Enable IntelliTrace".


Do you have enabled FusionLog?

My VisualStudio was very slow to start, open solution and load symbols when start debugging. It was slow only on my machine, but not on other machines.

FusionLog writes tons of log stuff to disk. Just disabling it on RegEdit solved everything, on my case.

This is the FusionLog key on registry:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Fusion

Check ForceLog value (1 enabled, 0 disabled).


I deleted the "Temporary ASP.NET Files" folder and my localhost page load improved dramatically. Here is the path... %temp%\Temporary ASP.NET Files\


For me, I implemented this tip which basically drastically improved performance by adding the following two attributes to compilation tag in web.config

<compilation ... batch="false" optimizeCompilations="true"> ... </compilation>

What does batch="false" do?

It makes pre-compilation more selective by compiling only pages that have changed and require re-compiling

What exactly is the optimizeCompilations doing? Source

ASP.NET uses a per application hash code which includes the state of a number of things, including the bin and App_Code folder, and global.asax. Whenever an ASP.NET app domain starts, it checks if this hash code has changed from what it previously computed. If it has, then the entire codegen folder (where compiled and shadow copied assemblies live) is wiped out.

When this optimization is turned on (via optimizeCompilations="true"), the hash no longer takes into account bin, App_Code and global.asax. As a result, if those change we don’t wipe out the codegen folder.

Reference: Compilation element on msdn


Here is how I solved the "slow symbol loading" problem in Visual Studio 2012:

  • Go to Tools -> Options -> Debugging -> General

  • CHECK the checkmark next to "Enable Just My Code".

  • Go to Tools -> Options -> Debugging -> Symbols

  • Click on the "..." button and create/select a new folder somewhere on your local computer to store cached symbols. I named mine "Symbol caching" and put it in Documents -> Visual Studio 2012.

  • Click on "Load all symbols" and wait for the symbols to be downloaded from Microsoft's servers, which may take a while. Note that Load all symbols button is only available while debugging.

  • UNCHECK the checkmark next to "Microsoft Symbol Servers" to prevent Visual Studio from remotely querying the Microsoft servers.

  • Click "OK".

From now on, symbol loading should be much faster.

Note that if you make any changes/downloads to Microsoft assemblies, you may need to go back into the Symbols dialog box and "Load all symbols" again.


Emptying the symbol cache worked for me.

See: menu bar / Tools / Options / Debugging / Symbols / Empty Symbol Cache


I don't know if you're still having this issue, but I debug sites in Visual Studio by attaching the debugger to the process itself rather than letting VS do it for me and I have found it to greatly improve times. I use an extension for VS called AttachTo and I have a small article on how I use it here.

I hope this helps.


There is also complications in partial views where there is an error on the page that is not recognized immediately. Like Model.SomeValue instead of Model.ThisValue. It might not underline and cause problems in debugging. This can be a real pain to catch.


One time, after a power outage, I had to face the same slowness problem each time a breakpoint was hit or a Exception was thrown.

I had the vague remembering that the "suo" file (in the same directory as the "sln" solution file) can be corrupted and make everything slow down.

I deleted my "suo" files and everything was ok. The .suo files deletion is harmless and only implies to recreate my windows layout plus the starting project and a few other non critical customizations.


The problem for me was the "Browser Link" feature that is very heavy when you have several tabs open for the same project !

Because every time we launched the project, it opens a new tab with browser link communications.

Just close all tabs associated with the project and keep only one open !

This free instantaneously visual studio ! It’s magic ! ;-)

“Browser Link is a feature since Visual Studio 2013 that creates a communication channel between the development environment and one or more web browsers. You can use Browser Link to refresh your web application in several browsers at once, which is useful for cross-browser testing.”


I had problems with slow Visual Studio debugging when "Native Code" debugger was enabled. Try disabling it.

On "Visual Studio 2012" go to:

  1. Project Properties ->
  2. Web ->
  3. Debuggers (bottom of page). ->
  4. Disable all except ASP.NET

Hope it helps.

Similar questions: 1, 2


Open the solution folder in windows explorer, close the visual studio, delete .suo file from windows explorer.

Now open the project in visual studio, hopefully debugger will attached/detached fastly.


I had execution perfomance troubles with debugging too and i tried very many options of debugger. In my case huge perfomance achieved when i change this options:

Tools - Options - Debugging - Output Window - (General output settings - All debug output) - OFF


Go to your environment variables and look for the key _NT_SYMBOL_PATH.

Delete it.

Voila, worked like a charm.


If someone notices this behavior coming out of left field, check to make sure you don't have any breakpoints set in web.config. I must have set one with a stray mouse click, and it really slowed down all debug operations.


I experienced the same problem and tried most of the resolutions above. Simply deleting cache and temp files end up working for me.

Try removing the contents of these two folders:

C:\Users\\{UserName}\AppData\Local\Microsoft\WebsiteCache

and

C:\Users\\{UserName}\AppData\Local\Temp (in particular the iisexpress and Temporary ASP.NET Files folders).

This can be set up to happen automatically on logging on to Windows by adding a cmd file to the C:\Users\\{username}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup folder with the following content:

rmdir C:\Users\\{username}\AppData\Local\Microsoft\WebsiteCache /s /q

rmdir C:\Users\\{username}\AppData\Local\Temp /s /q

The above are all good solutions and I tried all of them, but got the solution here, which is to

Debug -> Delete All Breakpoints

After spending all day waiting for symbols to load as slow as turtle speed, mixing and switching between all the possible combinations: Just My Code, Caching symbols, Intellitrace, Just-In-Time, killing processes, etc.

My solution was actually to disable the antivirus. Yeah, Windows Defender was slowing my project launch! It would check all the dlls as Visual Studio requested them and slowed the whole symbol load process.

I have to say our machines have great specs to compile the solution really fast, so that was never a problem. We code in VS 2013 Ultimate.


In my case I noticed that disabling my internet connection would make it run as fast as with ctrl-f5, so I went to debug->options->symbols and just unchecked all .pdb locations.

Seems like VS was trying to connect to these servers every time a debug session was launched.

Note that disabling Debug->Options->Debugging->General "Enable source support" or "Require source files to exactly match the original version" wouldn't make any difference.


My slow VS issue was resolved by disabling the Browser Link


In Visual Studio:

Tools -> Options -> Debugging -> Symbols

Choose "Only specified modules". Click the "specify modules" link, and add a blank module (click the new document button and hit OK).


Build solution will build any projects in the solution that have changed. Rebuild builds all projects no matter what, clean solution removes all temporary files ensuring that the next build is complete.





asp.net-mvc visual-studio visual-studio-2012 iis-express cassini