http://www8.hp.com/us/en/software-solutions/digital-user-experience-management/index.html?originid=510072802&jumpid=em_c4t1dq9ujx#community

Can your application keep up with the speed of user demand?
End-users want speed. If your load times are more than four seconds or if it takes more than two seconds to move from screen to screen, they will stop using your application. Mobile has increased user expectations, and there is a sense of immediacy with everything. These demands mean that you have to build, test and release quality software and applications faster—and more frequently.

This increased speed and velocity requires rapid feedback. With frequent releases you need to have feedback loops that keep pace. Without constant updates and patches, your applications will be vulnerable to slow operations and will be dropped by users. This is where testing plays a role.