It's not inherently slower, however you have to add extra logic to correctly handle overflows and the like. However given the size of modern floating point unit

It's not inherently slower, however you have to add extra logic to correctly handle overflows and the like. However given the size of modern floating point units I doubt it's a massive overhead. Basically they would need to convert back and forth between the native zeros and ones of hardware and the decimal representation. And extra logic might mean slower hardware in certain circumstances. Basically try to implement a BCD counter in verilog and you'll see where the overhead appears compared to a "dumb" binary counter. In practice it would be slow because not a whole lot of CPU architectures natively handle BCD. If this "standard" goes mainstream maybe the vendors will adapt and make special purpose "DEC64 FPU" hardware. I'm not really sure what's the point of using this floating point format outside of banking and probably a few other niche applications. For general purpose computing I see absolutely no benefits.