This is a bit of a rant.
I see this every where and it makes me want hulk smash things. If you are performing a task asynchronously in response to a user action, you should be providing some type of visual clue that the action is being performed.
Lets look at an example of what I mean. Here is a bad user experience:
Its very easy to fix, here is a minimal solution:
This is particularly important for mobile devices where network speed can be pretty slow. Don’t leave your users wondering if its broken.