Program is faster when launched from VTune

Hi,

I've noticed that if I time my program launched from the command line, it is slower than when I launch it from VTune (~25sec vs ~18sec). I've already checked that I'm running the same binary with the same options. Also, when I run it from the command line I run it 5 times consecutively.

I've noticed that, when launched from command line, the CPU stays in "slow" mode (at 1600MHz measured by CPUz), but when launched from VTune the CPU enters "turbo mode" (goes up to 2400MHz measured by CPUz).

Any ideas about why this is happening?
Does VTune launch my program in some special way to trigger the "turbo mode"?

Thanks in advance

PS: my PC is an Intel Xeon E5620 running Windows7 64bits, in case it helps