=======================================================================
speed of KLT versus OpenCV feature tracker on a 2.8 GHz P4 computer:

                        KLT      OpenCV
---------------------------------------------
track (100)             54 ms     47 ms
track/replace (100)     95 ms     82 ms
track (1000)            79 ms     59 ms
track/replace (1000)   139 ms    103 ms

The number of features is given in parentheses.  These times were computed by running the code on the same image multiple times in succession, then averaging.  As a result, they may not reflect the overhead of loading the image and cache misses that would occur in a real scenario.
=======================================================================