One thing, though: "Fast programmers" are not monolithic. Yes, you will be faster in an environment where you are not constantly looking up API functions. The world's fastest Perl developer that has never encountered Erlang is not going to turn into a fast Erlang developer overnight. He'll learn Erlang better than a novice will given the same amount of time, but it will still take time.
"Practice, practice, practice."
One thing, though: "Fast programmers" are not monolithic. Yes, you will be faster in an environment where you are not constantly looking up API functions. The world's fastest Perl developer that has never encountered Erlang is not going to turn into a fast Erlang developer overnight. He'll learn Erlang better than a novice will given the same amount of time, but it will still take time.