I don’t really like Zoom, but I was on a call the other day with 3 other people calling from phones and iPads, all using virtual backgrounds. You don’t need beefy specs to use the feature.
It wouldn't make sense for other people using the feature to take any more processing power--I assume the video is encoded and processed the same either way.
Another poster mentioned though that Zoom required green screens for this feature on non-intel CPU machines.