profiling is not a replacement for user feedback. You could profile some server side functions and see that X is 5 ms and Y is 8 ms. You will think all good, they're pretty fast. But the user might complain about a feature being slow, say deleting a thread, which happens to call the 5 ms function 50 times for some reason. You would then address the reason for so many calls, rather than optimizing the call itself.

Talking to your users is paramount, at the very least they will indicate where you have to add profiling