Power consumption in a CMOS MCU is theoretically given by the formula:

P = f * U2 * k

where f is the clock frequency, U is the supply voltage, and k is a constant.

Power debugging lets you verify the power consumption as a factor of the clock frequency. A system that spends very little time in sleep mode at 50 MHz is expected to spend 50% of the time in sleep mode when running at 100 MHz. You can use the power data collected in C-SPY to verify the expected behavior, and if there is a non-linear dependency on the clock frequency, make sure to choose the operating frequency that gives the lowest power consumption.