GoDaddy is adding its own traffic tracking code, called RUM, to web sites that it hosts.
The code generates javascript to take advantage of Real User Metrics, and apparently web sites are opted in by default.
GoDaddy uses Real User Metrics by default – Photo by Thomas Kvistholt on Unsplash
Such code has the potential of slowing down web site performance, and can sometimes break web sites.
According to GoDaddy, all data collected by its proprietary RUM code is utilized to improve its systems and server performance.
RUM is a variant of Real User Monitoring.
Long story short: RUM provides no real benefit to the GoDaddy customers, and opting out of it is a three step process, explained here.
As an added note, the domain RealUserMetrics.com is currently not registered.
Update: Someone registered the domain RealUserMetrics.com after the publication of this article.