Actually, the most monstrous pig in Visual Studio for me is SSDT (Microsoft's SQL-code development environment within VS). That's a bit offtopic since it's for SQL development and not C#, and they made a little bit of improvement in 2015, but still: it's a pathetic monster.
In general, anything that tries to pop-open a GUI and just drags makes me roll my eyes. EDMX files, I'm looking in your direction.
SSDT is insanely slow rebuilding our database model in the 'background'. And it's clearly tripping over itself somewhere because system CPU and IO is typically near zero while these rebuilds are running. Very annoying.
VS2015 improved SSDT builds, I think. Build times were cut in half, but memory usage skyrocketed. I'm supporting a legacy system that used to be north of an hour to build under SSDT. Now it seems closer to 20 minutes, if it doesn't get "Out of Memory".
I do think it maxes out 1 CPU, it's just single-threaded.
This is not necessarily true, especially with VS2015 RTM (Update 1 is a bit better): https://twitter.com/hmemcpy/status/687257223081377792
> This is not necessarily true
Can you please clarify which part? The linked tweet talks about Roslyn. I'd expect that to be loaded because ... it's not third-party.
Yes Roslyn is first party and it naturally does load, and it's very memory-intensive. You can see it happening without any extensions installed.
[1] https://msdn.microsoft.com/en-us/library/ms241278.aspx