Let me start with saying that I believe that C# is the best computer language ever made, it has really made me love my job.
I also program quite a fair amount in C and C++ and the one thing that really bothers me about C# is the (startup) performance.
Now I know that Microsoft has come up with C# Native, which uses a AOT (ahead of time) compiler to compile the C# source code to native machine instructions. However, at the moment it only supports UWP, which is a small subset of .NET projects. Development also seems to have stalled, as there hasn’t been any progress on C# Native for years.
I would hereby like to urge Microsoft to continue working on C# Native and to make it available for all types of projects, including WPF, WinForms and ASP.NET.
I believe C# Native could be a game-changer in that it could supplant C++ as the language of choice for most development, even at Microsoft internally. Products like Word and Visual Studio would be much easier to develop with C#, especially in combination with unit-testing.