On: Should array length be stored into a local variabl...

[l-]

TL;DR: Yes & use foreach rather than for to skip array bound checks.

[gameswithgo → l-]

it will skip the array bounds check as long as myArray.Length is the terminal condition in the for loop, rather than a local variable with the length stored.

[yc12340 → l-]

It is odd, that C# needs foreach loop for bound check elimination.

Java supports this optimization for a wide range of loop types... since Java 7, I think. Normally I would argue, that Java is just ahead of curve, but Android has also gained supports for bounds check elimination in 2014-2015.

Either article does not tell us whole truth or Microsoft JIT is subpar by modern standards.

[gameswithgo → yc12340]

c# does not need a foreach loop for bound check elimination.

[vardump → l-]

Yeah. A slight oops from CLR optimizer, but nothing serious. It seemed to miss a hoisting optimization opportunity in the foreach case.

[Gibbon1 → vardump]

Long time ago I decided that you shouldn't second guess the compiler without a reason. So just avoid worrying about local optimizations and focus on your data structures and algorithms.