Great blog post by the founder of 4chan.
A few highlights:
When considering a domain to use, I had the option of choosing between a longer domain (ie. images.4chan-cdn.org) and a shorter one (ie. i.4cdn.org). The average page may have ~125 or so of these links, and the difference in page size between the two is around **~50 bytes compressed**. 50 bytes may not seem like a lot, but when you're serving 500 million pageviews per month, it adds up. This small change will save us about 23 gigabytes of transfer per month, and **~275 GB over the course of a year**.
I guess its a bit like the legend about an airline saving millions (or at least tens of thousands) by just eliminating one olive per meal on its first class flights.
Tiny changes at scale really add up.
Google Analytics puts the average user's **cookie size around 1 kilobyte**. Because these cookies are sent with every request made to content hosted on 4chan.org, the average user must send 4chan roughly 100 KB of data per page load to receive the response. … By migrating to the new domain, end users now save roughly 100 KB upstream per page load, which at 500 million pageviews per month adds up to **46 terabytes per month** in savings for our users. I find this unreal.