Thanks again for this very helpful guidance. I feel like I can now see my fundamental misunderstandings in terms of ranks and positioning. A lot of my naive observations seem to make sense now, which gets a lot of thoughts rolling.
I started to correct my minlen calculation to integer values. This also allowed me to finally fix carrying over fractional time parts into the next rank. Now the minlen also more clearly relates to the “base unit” of the graph, which is neat. However, this had no noticeable impact on rendering performance, of which there was no expectation.
The real suggestion was to drop minlen anyway, so I also did that. The result is surprisingly pleasing, given how much importance I placed on this detail of my graph. This is giving me food for thought. At the very least, this will be my new default preview version to use while working on the data. Awesome!
Given this output, I can also better understand the suggestion to work from this version and just adjust the position according to time scale in a later step. This seems much more feasible than getting used to renderings taking in the area of days.
For clarity, the graph and the data sets on GitHub are only for public discussion of the project. There is a real data set, with private information that details my own entire life, and that of people related to me, which is merged with the public data to create the real image. In that version, the edges of the individual timelines also merge into single nodes, if timelines have shared entries that would result in duplicate nodes. The 10h benchmark is for the public data set. The private data set hasn’t been rendered in weeks. I assume it heavily outweighs the 20K ranks.
It was actually very hard for me to reproduce my problems with the public data set. For the longest time, it just would not work. Until I decided to add the start of the UNIX epoch as a world event the other day. I didn’t understand that fully at the time, but somehow realized that my private data set problems also started when I added the birth date of parents. This had already confused me, but I assumed it was somehow a result of the timestamps being negative, and me not handling time travel properly in my own code.
I now understand (hopefully) that the answer is simply the minlen forcing thousands of empty ranks at the start of the graph. Which also answers why another one of my performance boosts was the logarithmic scale for event spacing, as that just results in less empty ranks as well.
I hope I can get to remaining suggestion soon, but your help might have already enabled me to pile on more data again 
@steveroush If I may ask, was the singer “Oliver” a big deal in 69? I came across him the other day while “time traveling”, and looking for who might have inspired my own name. My senses tell me you mentioned that specific year, because you have required information to solve this side quest