Nobel-prize winning economist discusses the Soviet economy and how it was once "one of the wonders of the world", demonstrating growth rates far beyond that of Western democracies even if you discounted the obvious Soviet exaggerations:

LIVING IN a world strewn with the wreckage of the Soviet empire, it is hard for most people to realize that there was a time when the Soviet economy, far from being a byword for the failure of socialism, was one of the wonders of the world--that when Khrushchev pounded his shoe on the U.N. podium and declared, "We will bury you," it was an economic rather than a military boast.

The short version of Krugman's analysis is that the Soviet Union was capable of rapidly increasing economic inputs: more trees cut down, more workers in factories, more ore dug up; and that explained the rapid growth. But such growth is limited and will reach diminishing returns. There are only so many trees you can cut down, so many people available to work in factories. Where the Soviets failed, and where western economies excelled, was in increasing economic efficiency, getting more for less.

The Soviets worked harder. Instead of serfs struggling only a bit beyond subsidence farming, they had factory workers building tractors. But Western economies worked smarter, which isn't capable of the enormously fast and high rate of growth that the Soviets experienced, but can continue much longer. Russians and other eastern Europeans enjoyed much improved standards of living, but those improvements stalled once the economy was working as hard as possible. Without the increase in efficiency, including technological improvements, there was nothing like the western system where consumer goods became cheaper and more efficient over time.

There's a joke from before the fall of the Iron Curtain that might give a flavour of Russian experience. It shouldn't be taken too seriously, but it does reflect the lack of technological progress. A West German and Russian business man meet up and the German decides to show off his brand new digital watch. He shows the Russian how the watch can tell him the time in ten different countries, and the Russian proudly points to his own digital watch and says "Mine can tell the time in twelve countries." The German shows how his watch has a stop watch accurate to a tenth of a second, and the Russian says his is accurate to a hundredth of a second. The German says his watch has five different kinds of alarms and reminders, and the Russian says his watch has ten different alarms, and can speak the time in four languages. The German reluctantly has to admit that the communists have built a better watch, and then asks the Russian what is in the two enormous suitcases he is carrying. "Oh comrade," the Russian replies, "they aren't suitcases, they are the watch batteries."