I run it at work on Xeon with SSD and 16 GB. Project sizes might be different. I don't have experience how the performance would scale with a project with tens of millions of lines of code, for example. (seems to be fine for me below that).
It does exhibit strange behaviour (including becoming suddenly very tardy) that only goes away by deleting the local cache files (intellisense db and whatnot) so I'm not claiming it's technically perfect.
It is meaningless to make such comparisons unless you also compare codebase sizes. VS is perfectly zippy if you have a small project - but try to hit CTRL+SPACE to complete an Unreal Engine or OpenCV identifier! You will be sitting there for 30 seconds or longer while VS is busy parsing/searching files ...
I don't have any third party software installed on top of VS2015.
Only unusual aspect is that I also have several other Visual Studio versions installed, like VS2008, VS2010, VS2012 and VS2013.
I also have many Windows SDK and DDK (driver devkit) versions.
But that shouldn't affect, right?