I'm using my data as internet. Here's how much data it takes to post on CE:

Beginning usage: 4.55 GB

I clicked "Make topic", made the topic, typed my text, and created the topic. I will edit to show the new usage amount.

4.56 GB.

it takes approximately 10 megabytes of data to make a single post on CE in Google Chrome, with nothing else running in the background.

That seems.....high.