Dell XPS 13 9343 clock multiplier limited to x15

If I boot my computer on battery power the clock multiplier is limited to x15. Presumably this is a speed-step thing to save power. however, if i plug in the (Dell-official and recognized) charger, I don't get an increase to x32. 

If i reboot the system with the charger plugged in, I can then get the full clock speed.

Is there a fix for this? I have the latest BIOS, power management, etc.