RBS 2019 - 400Mhz on Battery?

I noticed today at work that on battery, my new RBS 2019 becomes very slow and unresponsive.

Looking at Intel Power Gadget, it appears that the CPU frequency is being capped at 400Mhz when on battery power and under load. When on battery and idle, CPU frequency is normal. CPU frequency is also normal when the AC adaptor is in use.

Any idea what might be going on here? This issue occurred before and after the recent Bios and EC updates.

EDIT: To add to the above, I think the frequency throttling may be due to the bd-prochot sensor firing off erroneously, as shown in the screenshot above.