Whatever it is, it has to do something with your PC or your project.
I am using Creator every day on a 3 year old HP ZBook with 64 GB of RAM and openSuSE Tumbleweed.
It literally takes milliseconds to find slot functions.
Besides, a nice feature for the Designer would be, if on can see in the slot list if a slot funktion exists yet. A * sign or so. Sometimes I have not the overview what kind of slots are connected und I must check it all - what is very slow now.
The widget designer shows a list of signals. You can use the autoconnect feature with the on_<ui-element>_<signal-name> syntax. You can also manually connect to a slot named differently. You can use multiple connections, which you set up and disconnect at run time. The "Go to slot" function just implements the autoconnect version in the cpp file that includes the code generated from the form. If the slot is already implemented, it makes Creator jump to it. The logic of when to put an asterisk isn't trivial.
The question makes me think whether the cpp file with your implementation is actually super-huge and somehow slowing Creator down.
Can you boil the issue down to a small, compilable reproducer?
