YouBoost is a potentially unwanted program that is bundled with free software you download from the Internet. Once running, YouBoost will donwload and use custom built Chrome browser called ChromeEx. ChromeEx is constantly connected to various sites on the Internet that constantly connects to. sites. When it connects to these sites, Youboost will display these page, including advertisements and videos, in the background. This constant downloading of web pages does nothing but slow down your computer and your Internet connection while providing no benefit to the user.
Source: https://www.bleepingcomputer.com/virus-removal/remove-youboost