No one suggested it isn’t censorship,
In fact, some replies suggested it’s more commercial actions. We said it's "likely influenced by commercial decisions", we didn't say censorship is out of the question. We still think censorship is the possible cause, but we run out of methods to verify it, that's why we switched to commercial actions to try our luck. If commercial actions don't seem to cause the slowdown, then it would be definitely censorship. 

Most of the performance hit is because of commercial actions, not censorship. 
When there is a tri-opoly, with no opportunity of competition, its easily possible to set prices which are very different than market conditions. This is what is happening here. 
Prices are set artificially high, so their interconnection partners wont purchase enough capacity. additionally, the three don't purchase enough to cover demand for their own network. Results in congestion. 
                                                                                                                                                   -- comment

what also doesn't help is that the Chinese carriers don't want to peer in Asia, not even with globally transit-free tier-1 networks. Their closest point of interconnection is typically in Europe or the US, so thousands of miles away from the end user. 
                                                                                                                                                   -- Anonymous comment
 
you’re bating here.
Once again we are confused by the accusation.  We don't want to bait anyone for anything.

Not deploying enough international capacity is absolutely a form or censorship deployed to great avail
 Yes we agree it is also a form of censorship. However, it is based on the assumption that China didn't deploy enough international capacity, which we don't have direct proof of it. On the contrary, from the stable performance of the traffic going out of China, it is very likely the assumption is not true. They might have enough physical capacity, but they don't make good use of it.