I'd suggest using timegm instead of mktime, or set the TZ environment variable to UTC to ensure all implementations return an identical date. I ran the same tes

I'd suggest using timegm instead of mktime, or set the TZ environment variable to UTC to ensure all implementations return an identical date. I ran the same tests and found that the strptime was quite fast, but gmtime was taking most of the time. To speed that up, you could borrow SQLite's implementation. Checkout the computeJD function from SQLite's date.c - http://www.sqlite.org/src/doc/trunk/src/date.c http://www.sqlite.org/src/doc/trunk/src/date.c