Chrome extension: getBackgroundPage vs sendMessage. Which method is better?

Question

JavaScript

The Chrome Extensions API has several ways to share data from popup to background.
Question in chrome.runtime.getBackgroundPage(...)and chrome.runtime.sendMessage(...). The first allows you to get a link to the windowbackground page, the second - send a message to those who subscribed to events.
As a person who has been writing client-server applications for a long time, I feel asshole that the second method is more correct to use, but I have no proof of this. On the contrary, I understand that sending messages and receiving a response is serialization / deserialization in the json of the request and response, when we receive a link to it when we receive the background page, and this should theoretically be less expensive.
Who knows how it is inside, how right?
Any thoughts?