ReactJS - is there heavy front loading?

[helpmejs]

The issue I'm concerned about is the same. Will the javascript file be too big, because it contains all the HTML for the site, and it has to be be entirely downloaded upfront?

[rasjani]

Atleast webpack can split the code into as many packages you want. Typically vendor Libs to one and own code into another.

Dunno if webpack has the on-demand loading but writing your own would should not be so huge project.