Question about Next Page Addon before purchasing

Hi!

I have some long posts that I would like to split into different parts and I have been looking at the Next Page Addon as a solution for me but I’d like to clear something first.

I’ve seen on the plugin description at WordPress that this plugin loads posts in lazy load. May I ask please if I purchase the Next Page addon, if the posts will be loaded entirely or it will only load part by part? I mean, if for example my post currently takes around 15 seconds to load, but if I split it with the Next Page addon, will it still take 15 seconds to load, or will it decrease to let’s say, 5 seconds?

I just don’t have clear if the page will load entirely or it will only load the content before the first “page break” block

Apologies if the question is silly but my knowledge in this is very basic and given the addon costs money I prefer to ask first.

Thank you very much for your time and I am looking forward to hearing from you.

Cheers!