Domain registrar GoDaddy injecting JavaScript into US customer websites that could impact the overall performance of the website or even render it inoperable. The code is part of the Real User Metrics (RUM) feature that monitors websites for internal bottlenecks. The feature is opt-out for US customers using cPanel Shared Hosting or cPanel Business Hosting. GoDaddy admits on the RUM support page that this code snippet “may cause issues including slower site performance
Source: security