I just looked at the two queries filtered for one of the participants with a well-filled timeline. So, there are two queries for that participant's timeline which each come back with 376 rows, 3 and 4 data columns respectively (4 and 5 if you count the ptid column). In our case that timeline is shown in a psuedo-tabbed ext panel set, so there is maybe a 20 second load that the user wouldn't notice unless they quickly jumped to the timeline tab as soon as the page loaded. We've been pretty happy with the performance and clarity of it, and the fact that it can be nested inside ext components and still work well.