C/C++ Integrated Development Environments (IDE) Resources

This is a known issue with VS 2015 and it could be caused by any number of issues. You can get some suggest work arounds here: https://stackoverflow.com/questions/31553560/visual-studio-2015-is-very-slow And yes newer version of Visual Studio have gotten much better about speeding up initial launch and in fact that was one of the primary focuses of the 2019 build: https://devblogs.microsoft.com/visualstudio/performance-improvements-in-visual-studio-2019/

It should be. Because Apple always support backward compatibility.

What OS/platform are you building software for? I believe that Eclipse has environments for just about all operating systems and platforms available.