Cloudflare is a great solution to speed up your site, but like other popular services in the world, it very slow, even blocked in mainland China. Enable cloudflare will slow down your site for the visitors from mainland China.
Cloudflare also provided the "Experience a Faster and More Secure Internet in China", Through theirpartnership with Baidu, they've created the only truly integrated global network that offers a fast, secure, and reliable experience for visitors inside and outside of China.
It sounds great, but the truth is that:all the web services in China need ICP license.
An ICP license is issued by China's Ministry of Industry and Information Technology (MIIT), and is required to host or cache online content within mainland China.
A valid Internet Content Provider (ICP) license is required to use the cloudflare in China. another word, if your site is hosted in mainland China, you can use the Cloudflare, otherwise, please don't use this feature to slow down your site speed.