I have a MVC4 Web project with Razor, which works fine in VS2012. In VS2013, after clean-rebuild, the same web project produce html with encoding issues. it
Could be the Browser Link feature in VS 2013. Look for this in your toolbar:
Uncheck Enable Browser Link and reload the web page (rebuild shouldn't be necessary).
I figured this out noticing a bunch of requests like http://localhost:64667/613318d74fb54ab5bed269c36eb39fde/arterySignalR/connect...
in Fiddler that I had never seen before. Also, using the Raw tab of the inspector in Fiddler showed lots of random unprintable bytes being injected into the HTML of my web pages.