I've been doing some optimization experiments on several functions in my app and monitoring the results with VTune v6.1. Recently, while trying to improve the performance of one of my functions I unrolled it twice. According to VTune sampling this decreased the functions clockticks by about half. However, when I ran the app and timed it with a stopwatch, it was considerably slower! How can this happen? Only the unroled function was changed, nothing else. Thanks.
Vtune shows improvement, but actual timing says otherwise