Just to be clear, we're using all the optimizations that we have empirically determined are safe to use that do not break your code. We spent many weeks testing various combinations to determine which could be used without wrecking the resulting executable. This included loop unrolling which is usually safe but not always safe. Some tests resulted in compile times measured in days. One of which resulted in a compile that was measured in weeks. Every test of different optimization settings was tested using our compiler verification test suite so we could be 100% sure that the resulting executable was in fact functioning as expected.