I ran one version of the code and it worked fine on my development machine.

Calling the GUI display function for each row is very CPU intensive. However this is not a "bad" idea. My Win XP laptop test machine has died. I lament that loss because if I can get the GUI to work on a very slow machine, it will work like magic on a fast machine. Sometimes we developers assume that the users have machines like we have (many cores, min of 16 GB memory), etc. That in general, is not true.

Unless you can calculate the whole thing in less than one second, I figure a more CPU intensive process that actually takes longer for the full result is generally better. If the UI "hangs" there are problems with that.