Microsoft's 90s Weapon That Made Windows Fast [video]

The baited answer is something I haven't run across before.

    a highly classified internal Microsoft project codenamed "Microsoft LEGO".
    aka: the Basic Block Tool (BBT).

    the BBT operated on the compiled binaries. 
    Shuffling the internal basic blocks of the code improved
    efficiency and sped up execution.

    a basic block is a sequence of straight-line code that has exactly
    one entry point and one exit point, with no jumps or branches 
    in between. Microsoft engineers could rearrange them within the
    binary to optimize how the processor handled the instruction