I was expecting it to keep 2million checkboxes updated in my browser. But looking at the websocket messages, it seems to only send updates about the slice I am

I was expecting it to keep 2million checkboxes updated in my browser. But looking at the websocket messages, it seems to only send updates about the slice I am looking at which consists of 1441 checkboxes at a time. https://i.imgur.com/uKH4wee.png https://i.imgur.com/uKH4wee.png