What is meant by lightweight theme technically?

Hi there,

Lightweight refers to the themes code base and therefore how quickly it can load.

Primarily the less requests a theme makes ( stylesheets and JS ) and the smaller those requests are will make the theme lighter.

We also have conditional loading - a poorly written theme will load code everywhere whereas GP is focused on only loading the code that a page needs.

And overall the code itself. Good coding standards will minimise server queries.