Amazon found that 100ms of additional load-time in commerce applications will reduce sales by 1%. (See line graph)
Yahoo found that 400ms of additional load-time results in 5-9% less user engagement.
According to Apptentive it costs an app $2.80 to acquire an engaged user.
For every $2,800 spent on acquiring engaged users, an additional 400ms of load time in your app will cost between 50-90 engaged users or about $140-$252, and the engaged users will spend 4% less.