I have quite a complex project that has a lot of elements (probably could be tidied) and have noticed the search time for the data picker slowing down dramatically. I have seen posts by others who have experienced this too.
What I have noticed is that when copy and pasting an id into the search, the result appears almost instantly. What it looks like is that it is starting a search on every key press. When each search takes a few seconds and you type several letters, it seems to be adding quite an overhead.
Just hoped that spotting this might help refine that element of the UI.