Idea- to add a smart list count (a little window or something) to the Smart List view, or add it to the first tab where all of your criteria are listed. This way you don't have to wait for the leads to load to see the count.
Example: I'm working through filtering out and cleaning up some of the database, I need to pull in new filters into smart lists and see what the numbers look like with different combinations of filters. For this, I don't really need to view the leads and their info, I need to get a feel of the quantity. This would help a lot time-wise.