Personally of the higher-level languages, I found SBCL to be crazy good at optimizing, of course given a few nudges with a compiler directive or two. By inspecting the dissasembly, I could validate it was doing the "right-thing" (TM), but then again, I do the same to check the C/C++ compiled code.
Yes; see also http://prog21.dadgum.com/40.html