Why is AFNetworking slower on devices than on the emulator?

Question

iPhone

There is a RESTful service API. The API is working correctly. Request processing time has been debugged. There are no hitches on the server.
The Internet is always the same. Distributed from phone to Mac and used on the same iPhone. 99% shows LTE.
And yet, the responses from the server sag on the device (sometimes they take more than a minute). In the emulator and through curl, requests come many times faster and there is no such problem.
The problem is floating. And the reasons are not clear. It shows up at different times on different devices.
Who faced prompt please.

Answer 1

If the server is hosted on Heroku, there may be periodic brakes due to the application going to sleep. About once every hour or two.