I\'m running Visual Studio 2013 Update 4 and have been seeing high CPU usages and noticeable delay on simple UI menu navigation and basic text editing.
Using ProcessExpl
Looks like this is caused by browserLink going rogue (or it was for me anyway)
You can disable it next time the issue occurs:
For me when I disabled it I immediately got my CPU back. I personally was linking to chrome though I'm not sure it makes a difference.
I guess if you use it hopefully it will be fixed in a new version...