Im interested to see lemmyui on this list.

How can I check this?

I tried loading (new) Reddit homepage, and based on Network tab in Firefox without any prior cache it transferred 19.20MB compressed to 15.29MB.
But that also includes any pictures shown.
Loading lemmy.world homepage transferred 5.88MB compressed down to 1.82MB.
old.reddit.com 2.82MB compressed down to 947kB. Quite a difference.

Just for comparison, loading Eaglercraft 1.5.2, a fully functional Minecraft JavaScript clone, complete with LAN multiplayer support took 8.35MB.

But what exactly is this measuring?