China is blocking Google API since 2014, this means long loading times for websites that include Map API or Fonts API. There is a workaround for this, since fonts.useso.com also provide the same font library (see libs.useso.com, fonts.useso.com respectively).
The following code
<link href='http://fonts.googleapis.com/css?family=Open+Sans:300,400,600&subset=latin,latin-ext' rel='stylesheet'>
<link href='http://fonts.useso.com/css?family=Open+Sans:300,400,600&subset=latin,latin-ext' rel='stylesheet'>
You could use a third party service to determine the user location and switch your font.
For example, you can integrate userinfo.io which is free. In this case, the location is determined based on the IP address so if the Chinese person visits from Europe, he will be located in Europe and the google fonts will be loaded.
Insert this in your
Disclaimer: I wrote and maintain userinfo.io