On September 20, 1987, two Chinese scientists sent an email to their German counterparts. Their email read:
“Across the Great Wall we can reach every corner in the world.”
Since then, China has undergone unprecedented investment in internet infrastructure. It has built fibre optic cables, established national telecom operators and reached an internet penetration rate composing of nearly half of it’s population.
A question that frequently comes up is: Why is China’s internet so slow to [insert western website here], and there’s a couple of reasons.
The first reason is simple: China is known to have engaged in throttling of websites like Google. The tactic is meant to deter users from using services not located in China, while maintaining the appearance that they’re not engaging in censorship. This has been widely acknowledged (see CFR).
Another reason is a bit more complex, and applies to all internet traffic including VPN and SSH traffic seeking to avoid Chinese censorship.
China’s internet is dramatically saturated. When you’re trying to accommodate for 500+ million internet users, you’re going to run into a number of bottlenecks.
To preface this, your internet connection doesn’t go to a central hub. Generally, your internet connection will be to a small ISP, which will rent a certain amount of internet connection to a larger ISP (such as an internet backbone), which will rent access to underseas internet cables and perhaps to an even larger ISP. There is much more to this, but your ISP will seek to find the fastest route to the website, that it has access to.
Evidently, China’s ISPs doesn’t have much infrastructure in terms of undersea cables. Much of China’s internet revolves around access to domestic websites. Chinese users use Baidu instead of Google, Taobao instead of eBay and Sina Weibo instead of Twitter. China’s ISPs generally invest in domestic infrastructure instead, which sees much more use and utilization. There is far more capacity for inter-China connections, and therefore your internet speeds will be far higher.
As well, China’s ISPs have a monopoly. There are only two ISPs, China Telecom and China Netcom. There is little competition to provoke them into greater infrastructure development, and internet users can’t vote with their wallets.
So when you use your internet connection to access something hosted in the United States, you’re competing with millions of other internet users within a woefully at-capacity underseas cable. Your internet will slow to a crawl, as well everyone else’s internet.
tl;dr Domestic Internet is faster because there’s more cables. You’re competing with a million people on a few cables for internet access (thereby overloading said cables) when you’re accessing western websites and servers.