Lag when reselecting the subject selector

When focusing on a selector other than the subject selector, and then refocusing on the subject selector there is a significant lag in the gui.
This is caused probably by repopulating the list selector with the query results.

2 ideas to fix this:

1. investigate what exactly is causing this delay, and if this can be fixed
2. Apply this mod to the code and see if it performs better:
At the moment, every user query (every type of a letter) reloads the list selector results list
also, focusing on a new selector, reloads the list selector with the corresponding results list.

Instead, have the list selector reload the list only when/if it is visible. This will result in
focus - O(1)
and also enhance filtering performance while the list selector is hidden.

3. Have 3 different list selector for each pane ? :/

Note: with the icons insertion the cost of loading results list will rise very high !
Have the list selector keep a buffer of item