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Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
@Gordon
The nRF52s have what are basically programmable NFC cards. They can only be read by a reader (they can't read other cards).
As @Robin says it may be that you could add a MOSFET to properly cut power to the NFC reader when it's not in use. You could also try and power the 3.3v directly from Espruino's 3.3v and skip out their regulator - since Espruino's one is almost certainly lower power.
However it's probably better to get some tools to start measuring before you do too much - you could end up wasting a lot of time on stuff that has little/no effect. Even using a multimeter measuring the power drawn by the NFC's VCC line could be a good first step.
Out of interest, what NFC reader are you using? Did you improve the existing Espruino libraries for it to allow you to read the actual NFC data and do power management? If so is that something that you might consider contributing back so I can include it as an Espruino library?