https://www.visualstudio.com/en-us/downloads/visual-studio-2015-system-requirements-vs.aspx
1 GB of RAM (1.5 GB if running on a virtual machine)
Does it mean the host requires 1.5GB and will probably use 0.5GB and allow visual studio to run in a 1GB virtual machine?
That is very little for the host, since Windows 7 itself on the host is said to require 1GB.
Looking at a similar question here, the questioner did not have that in mind and so didn't request an answer to that in any answers.