performance on AMD and Windows

[BrannonKing]

lbrycrd runs slower on (modern) AMD processors than it does on modern Intel processors, even with SHANI enabled on AMD. It may be that some of the hand-tweaked optimizations are specific to Intel. This should be explored.

lbrycrd runs slower on MS Windows than it does on Linux. I thought it was an issue with the cross compiler, but it's true even when compiling with MSVC. In fact, the cross compiler does better than MSVC.