IIRC, China's communist economy has been growing faster than most/all lately.
Except for a couple of factors:
- It's debatable how "communist" the growth part of the Chinese economy is, since they've allowed millions of people to behave, and profit, as though they are capitalists
- The USSR had impressive growth for a generation or 2 as well. Didn't last. And the reason is that people weren't free enough to change things.
- It's easier to play catch up then it is to lead. What will they do when they can't copy any longer?
The growth is due to massively abundant fossil fuels. You can pull 40,000 pounds six or seven miles on a milk bottle fuel of liquid. In five or six minutes. As opposed to it taking either thousands of manhours or a whole caravan of horses (all requiring water & food).
There are other sources of energy made available by the science that came with modern economies.
This newfound ease with which we could grow crops, transport ourselves, create new materials (plastics & other synthetics) combined with new technology is what caused the growth (in rich countries, along with massive poverty elsewhere), attributing it solely to capitalism is intelligently dishonest at best (or ignorant).
What else can you attribute it to?