### 3.2GHz and 3.6GHz, no big difference?

I had an interesting discovery about my AMD Phenom II X6 1090T CPU. I threw a very CPU intensive job to it. But the time (measured in Linux command time'') spent to finish the job was the pretty much the same when the CPU works at 3.6 GHz and 3.2 GHz (I played a trick in AMD Cool'n'Quite setting in my BIOS and verified the frequency for the core running my job by cat /proc/cpuinfo | grep -i "cpu Mhz").

So, I am wondering why. I do not think it is because of the bottleneck at the memory. My program only uses 3% of the memory which in total is 8 GB.