Did you try itertools.imap instead? Vanilla map gives us a list; imap gives us a generator. (Also, I'd try a generator expression as well to see how it compares to a list comprehension).
Also, note that the article is from January 2007; I'd wager that Python has evolved and had a wealth of optimisations since then, especially regarding "common idioms" such as vanilla string concatenation and list comprehensions.
Also, note that the article is from January 2007; I'd wager that Python has evolved and had a wealth of optimisations since then, especially regarding "common idioms" such as vanilla string concatenation and list comprehensions.