Performance cookies are used to understand and analyse the key performance indexes of the website which helps in delivering a better user experience for the visitors.
The cookie is set by Google Analytics and is deleted when the user closes the browser. It is used to enable interoperability with urchin.js, which is an older version of Google Analytics and is used in conjunction with the __utmb cookie to determine new sessions/visits.
Google Analytics sets this cookie to inhibit request rate.
Google Analytics sets this cookie to store the traffic source or campaign by which the visitor reached the site.