The great thing about Annoy is that you can write the index to disk and thus do big data work on tiny workers at the edge. I've never really seen anything else do the same.
As far as I can see, Voyager requires you to load the index into memory and doesn't (yet?) do mmap. Which... would make sense since you can change the data after loading the index. So, Voyager index files are fully loaded in memory..? Do I have this right?