Visual Studio 2015 Update 1 spamming localhost

This is the debugger sending information back to VSHub process. It's internal communication between the two processes so that part of the debugger data collection can happen out-of-process.

It helps with debugger tooltips, performance information, the historical debugging experience and more. As such there's no way to turn it off without seriously crippling the advanced debugger features.

You can turn some of these features off (though other features may still rely on Vshub to do out-of-process work in the background):

Tools > Options > Debugging > General > [  ] Enable Diagnostic Tools while debugging

The communication is purely local and doesn't pose a serious overhead or issue. Is there a specific reason you want to get rid of it? Tools like Fiddler can be configured to filter on process, so ignoring this traffic should be simple.

Another option for preventing fiddler from chewing up your CPU is write a rule in fiddler to ignore those requests. Goto Rules > Customize Rules... find the function OnBeforeRequest and add

if(oSession.oRequest.headers["host"]=="localhost:49155"){
    oSession["ui-hide"] = "true";
}

so mine looks like this:

static function OnBeforeRequest(oSession: Session) {
    if(oSession.oRequest.headers["host"]=="localhost:49155"){
        oSession["ui-hide"] = "true";
    }
}

as @matrixugly pointed out the port can be different depending on the version of VS. @tedd-hansen's solution might be better across all versions of visual studio.

if(oSession.oRequest.headers["host"].StartsWith("localhost") 
    && oSession.PathAndQuery.StartsWith("/vshub/")) {
    oSession["ui-hide"] = "true";
}

Here's some discussion about this issue on github to get a better understanding of what's going on; https://github.com/aspnet/Mvc/issues/3655

Here's another post on SO for the same issue; visual studio 2015 vshub is spamming fiddler