ADE78xx: 0-Crossing for xIRMS registers

Hello,

In the datasheet (https://www.analog.com/media/en/technical-documentation/data-sheets/ADE7854_7858_7868_7878.pdf, page 44), it states that it is recommended to "read the rms registers synchronous to the voltage zero crossings to ensure stability". It does however not state what kind of instability I should be expecting if I don't read at a 0-crossing. For the hardware solution I am using, I will not be able to handle an interrupt on every 0-crossing for all three phases.

Why would reading a xIRMS register at a random moment be a problem? How big is this instability? Are there any alternatives to reading at 0-crossings?

Thank you in advance,

Marvis