You are viewing that data somewhere, either a website or an app on your phone or both. Ofcourse if you are doing a bunch of calculations on the client your PC will be faster. That has little to nothing to do with the tiny difference in internet speed/reliability (especially if we are talking minute based data).

If the above site is slow/crashes, its shoddy code work. They are doing way too many calculations on the frontend instead of on the server, or they are sending way too many requests (like many requests each second).