Every 100ms of latency costs Amazon 1% in sales

How critical is Mobile browser testing and mobile performance:

Every 100ms of latency costs Amazon 1% in sales. Pinterest optimized their website performance which led to a 15% increase in SEO traffic. 79% of users who experience slow page loading times are less likely to buy from the same site again, while 27% are less likely to buy from the same business’s physical store. As page load time goes from 1s to 5s, the probability of bounce increases by 90%.

53% of mobile site visits are abandoned if a page takes longer than 3s to load.