Searching overrides takes too long when pressing "follow symbol under cursor"

There are some projects, when searching overrides might take too long.

For example (you can use any other large enough project or something else inside of Qt):

1) Launch QtCreator

2)  Open qtbase/src.pro

3) Navigate to acoreapplication.cpp:1532 (or somewhere around)

4) Try press F2 on self->compressEvent from the following line:

&& self && self->compressEvent(event, receiver, &data->postEventList)) {

Actual: You'll have to wait around 65 seconds (for 4.7.1, or 40 seconds for 4.8 beta) to get all overrides

Expected: You should see all overrides almost instantly (yes, sounds optimistic, but it's desired at least)

I see the following solutions:

1. Implement fast lookup (are there any limitations?)
2. Display each new override once it found, without waiting the search end
3. Cache the results somehow, because the time doesn't depend on attempt now