Reminds me of the hilarious column by James Mickens, "The Slow Winter", on how these kinds of improvements used to be easy:

"“I wish that we could predict branches more accurately,” and you’d think, “maybe we can leverage three bits of state per branch to implement a simple saturating counter,” and you’d laugh and declare that such a stupid scheme would never work, but then you’d test it and it would be 94% accurate, and the branches would wake up the next morning and read their newspapers and the headlines would say OUR WORLD HAS BEEN SET ON FIRE."

PDF: https://www.usenix.org/system/files/1309_14-17_mickens.pdf