Difference in CSC and Roslyn compiler's static lambda expression evaluation?

Question

Consider the following example code.

class Program
{
    static void Main( string[] args )
    {
        DoSomethingWithAction( i =>
            {
                


        

Answer 1

This was a deliberate change made by the Roslyn team.

Delegates that point to instance methods are slightly faster to invoke, so Roslyn now compiles lambdas to instance methods even when it doesn't need to.

See discussion.