«it turns out today a top consumer (not HEDT) CPU barely matches this pair of CPUs»
Well, the X5670 was a high-end 2P server CPU sold for $1400 (https://ark.intel.com/products/47920/Intel-Xeon-Processor-X5...) so to fairly measure how performance has improved, you should compare it to a similarly priced product, like the AMD EPYC 7401 (https://www.amd.com/en/products/cpu/amd-epyc-7401). And, oh, look at this: the SPECint_rate "h264ref" benchmark subcomponent, which measures multithreaded video encoding performance, shows a 4.2× improvement (472 to 2000):
Edit: oops, fixed major screw up. I had linked to SPECint numbers, instead of SPECint_rate. The real improvement is 4.2× not 45×! Far from what Moore's Law predicts (2^(8/1.5)) but still a very notable improvement. I'm sure your friend would be happy to transcode 4× faster...
2x or 4x doesn't matter , you'd need magnitudes of difference to need to think what an OS can or can't do. Which is what the old ten year was about -- and look, 2^(10/1.5) is a bit above 101. Two magnitudes. That matters.
To compare, let's presume (this is a great exaggeration I know but it serves the purpose) each Chrome tab takes equal CPU time. Say, on the current computer the 100th tab makes it unusuably sluggish. At 2x, the previous computer could open 50, even at 4x we are looking at 25. At 100, we are looking at not being able to run Chrome.
Is it possible to buy a Mac Pro with an AMD EPYC 7401 CPU? Surely the fairer comparison would be against the current top-of-the-range in Apple's lineup.
Except the Mac Pro hasn't been updated in a while, partially due to thermal constraints. That isn't related to long-term progress, but an uneven cycle.
Well, the X5670 was a high-end 2P server CPU sold for $1400 (https://ark.intel.com/products/47920/Intel-Xeon-Processor-X5...) so to fairly measure how performance has improved, you should compare it to a similarly priced product, like the AMD EPYC 7401 (https://www.amd.com/en/products/cpu/amd-epyc-7401). And, oh, look at this: the SPECint_rate "h264ref" benchmark subcomponent, which measures multithreaded video encoding performance, shows a 4.2× improvement (472 to 2000):
• X5670: https://www.spec.org/cpu2006/results/res2010q2/cpu2006-20100...
• EPYC 7401: https://www.spec.org/cpu2006/results/res2017q4/cpu2006-20171...
Edit: oops, fixed major screw up. I had linked to SPECint numbers, instead of SPECint_rate. The real improvement is 4.2× not 45×! Far from what Moore's Law predicts (2^(8/1.5)) but still a very notable improvement. I'm sure your friend would be happy to transcode 4× faster...