Visual Studio 2015 Update 2 fixed this issue! Install Update 2 and you should be good to go.
Direct download: http://go.microsoft.com/fwlink/?LinkId=691129
Update 2 Release Notes: https://www.visualstudio.com/news/releasenotes/vs2015-update2-vs
Edit: "fixed" may not be entirely accurate, and it may not be entirely fixed for all users. Maybe we can pin down what everybody's experiencing. To clarify, my experience has been as follows:
- Prior to Update 2, VS would run 'npm install' every time I opened
the .sln, which was very hard to cope with.
- After Update 2, VS runs 'npm install' in certain scenarios, which is tolerable (in my experience.)
In my experience, post-patch VS will, upon opening the .sln, run 'npm install' if any of the dependencies in package.json are missing from the node_modules folder (or if the folder itself is missing.)
You can't disable the 'npm install', so 'fixed' may not quite be correct - however, it doesn't do it on every launch as before, so I consider it a win. Can folks confirm this is the behavior, or are we experiencing different behaviors?