In the Profile pane in Prep Builder we can use up and down arrows to navigate through values, this is particularly useful when there are a lot of values in the list and it's hard to click on exactly the right section in the histogram.
However when we do Prep takes a split second to update the colors for the window and when trying to move quickly Prep will not speed up, it will also lose key presses. Here's a GIF where I'm pressing the down arrow almost as fast as I can but Prep is taking it's own sweet time. (This is on a fully spec'ed 2019 16" MacBook Pro on a 4K record/4 column data set):
There were 20+ down arrow presses that were lost. By way of comparison here's MS Excel that is moving as fast as I can press the button.
In both cases there were about 16 items gone through and Prep is quite a bit slower, please make Prep faster. I know Prep is doing more because it's also updating the selection in other fields in the view, and I think it could be faster.