face detection application multi-threaded or not ?

edit

i tested facedetect.cpp and the output is like below

Video capturing has been started ...
detection time = 492.357 ms
detection time = 71.8476 ms
detection time = 81.1626 ms
detection time = 85.015 ms
detection time = 83.3563 ms

then i add setNumThreads(0); at the beginning of the code to disable multi-threading and the output is like below

Video capturing has been started ...
detection time = 688.146 ms
detection time = 258.817 ms
detection time = 298.695 ms
detection time = 334.468 ms
detection time = 185.794 ms
detection time = 222.631 ms