1) The USSR in Stalin's time set higher economic growth rates than the U.S. ever did. It was also the first country in space.
2) It fell behind due to the inefficiencies of the Stalinist regime, which was able to parasitize the revolution by taking advantage of its political weakness.
3) U.S. capitalism doesn't stand on its own. American capitalism is what it is because Mexican, Indian, and Haitian capitalism are what they are. More concretely, the U.S. enjoys the advantages it does because it forcibly maintains other countries in a disadvantageous position. You are comparing the first attempt at a workers' revolution, in an economically underdeveloped, politically benighted, war-ravaged country (a revolution which was then faced with overwhelming and merciless counterrevolutionary force), with a single empire that essentially monopolizes all the wealth of South America and much of the wealth of Africa and Asia, which has only recently passed the height of its power. By the same argument democracy is a failure because George Washington's men at Valley Forge didn't live as well as the ancient Romans.
4) I don't dispute anything related to the UN report on N. Korea. I certainly would never characterize the country as a "paradise." I take note of the deliberate starvation of political opponents of the regime, and retract the claim that there is not starvation in N. Korea (I meant, however, that there is not a generalized famine).