Over the past few years Microsoft has made significant effort to reposition Visual Studio as the premier developer tool for Windows, regardless of what platform the user is targeting. The recent acquisition of Xamarin and the strong support for open source tools to support non-Windows devices has greatly increased its usefulness to developers of all stripes. The downside to this approach has been an ever-growing size of the typical Visual Studio installation, which only swells as additional platforms are selected for installation. Even worse, Visual Studio's footprint is not limited to the disk space it consumes, as it also impacts the Windows registry and the GAC (global assembly cache).
With the successor to VS2015, currently given the moniker Visual Studio “15”, Microsoft intends to adopt a new philosophy. Microsoft's Art Leonard states that until now VS was deployed with regard to how quickly a developer could open a project and press F5 to have it built without any additional steps. The result is what VS provides today, an install process that is lengthy in both time and disk space. With VS “15”, the goal is to quickly provide only what the user asks for, with the remaining components available for installation when needed.
An additional benefit of this new approach is that Leonard says Visual Studio will be designed to be fully contained within a directory, with a minimal impact to the system as a whole. By default, this means that VS “15” will not be adding large quantities of data to the registry, nor will it be adding VS-specific assemblies to the GAC. The net result is that the base install of VS ”15” (consisting primarily of just the VS editor) is approximately 325 megabytes. If you are interested in reviewing different installation sizes, you may review the dependencies and corresponding disk usage provided by Microsoft.
One area for improvement that the follow-up comments address is how to deal with the SDKs and platform tools (emulators and the like) that are installed along with Visual Studio. At present, the improvements discussed above focus on VS “15” proper. Leonard remarks that the team is still investigating on how to handle this—as they do not want to allow an SDK to be removed by VS that is still in use by a different application.