s5Mark is a potentially unwanted program that is bundled with free software you download from the Internet. Once running it will donwload and use Chrome browser called cpx.exe that constantly connects to various sites on the Internet. This constant downloading of web pages does nothing but slow down your computer and your Internet connection while providing no benefit to the user of the computer. The only activity we saw was its constant connection to sites to watch videos and display advertisements. This is a type of web proxy, allowing the user to connect to the Internet through another computer.
Source: https://www.bleepingcomputer.com/virus-removal/remove-s5mark-and-cpx.exe/