“The Great Firewall of China” isn’t necessarily what makes your website slow. It is a set of very strict Internet content laws in China that makes you run the risk of your site being blocked or blacklisted if you don’t have an ICP license.
The reason for your slow site is the physics that even the Internet abides to. The distance between the content in your origin server and end-users in China builds latency. If you’re concerned about your site’s latency, I suggest doing some research on a content delivery network that performs well in China if you haven’t already. Here’s a really helpful source: http://www.cedexis.com/reports/#?report=cdn_response_time&country=CN&date=2016-01-17
You can either host your site in China and acquire an ICP or ICP Beian license, or consider a near-China solution, which I’ve elaborated in Quora: http://qr.ae/RONLWc