Do redundant casts get optimized?

Question

I am updating some old code, and have found several instances where the same object is being cast repeatedly each time one of its properties or methods needs to be called. E

Answer 1

A spot check on the generated machine code in the Release build shows that the x86 jitter doesn't optimize the cast away.

You have to look at the big picture here though. You are assigning properties of a control. They have a ton of side-effects. In the case of DateTimePicker, the assignment results in a message being sent to the native Windows control. Which in turn crunches away at the message. The cost of the cast is negligible to the cost of the side effects. Rewriting the assignments is never going to make a noticeable difference in speed, you only made it a fraction of a percent faster.

Go ahead and do rewrite the code on a lazy Friday afternoon. But only because it is a blight to readability. That poorly readable C# code also produces poorly optimized machine code is not entirely a coincidence.