We coded the given map/reduce example (http://api.mongodb.org/python/current/examples/map_reduce.html) directly in python and got much better performance (see attached script) ... did we get anything wrong?

Usage of the script (will create sample data and time the two methods):

python mongo_map_reduce_counter.py test_db_name

Example output (with nb_objects=5000, nb_tags=200, nb_bins=3):
$>python mongo_map_reduce_counter.py test_sdsd
calc naive time 0.317932844162
calc map_reduce time 110.605533838
Same results? True