Its not just the compiler - MSVC like all others has a tendency to mangle code in release builds to such an extent that the debug info is next to useless (which to be fair is what I asked it to do, not that I fault it).

Now to hate a bit on MSVC - its Edit & Continue functionality makes debug builds unbearably slow, but at least it doesn't work, so my first thing is to turn that thing off.

Which is why recent versions have dynamic debugging mode.