Google chrome's console says:
A parser-blocking, cross site (i.e. different eTLD+1) script, https://ssl.google-analytics.com/ga.js, is invoked via document.write. The network request for this script MAY be blocked by the browser in this or a future page load due to poor network connectivity. If blocked in this page load, it will be confirmed in a subsequent console message. See https://www.chromestatus.com/feature/5718547946799104 for more details.