Wow, thanks for the detailed review! Really happy to hear you like our tool, thanks for the kind words :)
We would very much like to show data about non-following users as well, but that's pretty challenging because as you also mention the app is already becoming a little slow.
Due to the way Steem makes its data accessible, we have to fetch information about users one by one. The more followers you have, the more information needs to be retrieved, making the app slower. This is why showing information for @ned takes so much longer to load than for @spectacles, because he has so many more followers. Adding data about non-followers as well could easily increase the amount of data needed tenfold or more, which would make the app so slow it's barely usable for users with many upvotes.
We're working on a solution for both, but it could take a while to realise. Thanks a lot for the suggestions though :)
I agree on fetching more data makes the app more slower. I think its better to track on user's followers than those who are not following yet upvoting some users regularly. Its better that way and that makes it unique than other steemtools.
I will be using this app regularly to keep on a spot to my followers and reward them because of their non-stop engagements. Thank you for the support @spectacles!