>In the 1950s, the Soviet economy grew faster than that of any other major country barring Japan. I'd like to read more about what was happening then, was it largely military investment?
The USSR also had many satellite nations, like the Eastern European block. Moscow was known to drain those countries' resources, with little local investment in return outside of military bases. I only have personal anecdotes to back that up having grown up in one of those satellite countries.
After the collapse of the Bloc most of those countries lost their industrial capacity, some have not yet recovered, some only recovered on outsource.