That calculation assumes that Go and Node have the same performance and the only gain is by parallelism. But I agree.. the performance difference seems strange. On a 1 core basis I'd expect something like a factor 2-5 gain.
Identical algorithms (e.g. quicksort) run ~40x faster in Go than Ruby in a single thread due to more efficient CPU usage, even when you avoid the kinds of steps that would allocate objects in Ruby. Multiply by 64 cores and it’s easy to observe a 1000x improvement with very little difference in the code.