dhenry:
The simplest approach to reduce current consumption would be to put a mcu into sleep / idle.The benefits of sleeping, however, maybe offset by frequent waking up.
Really? There is little overhead involved in sleeping the CPU and waking it again.
In that case, think of using a rc filter and a few mcu pins to dynamically throttle the clock speed.
Have you done this, or can you reference such a circuit? Sounds dubious, or at best a lot of trouble, I might just adjust the CLKPR register if I wanted to slow things down.