Thanks Kingsley, Thomas, Jeff,

From what I see the live query never is sub second and that's likely because of 2 things:

  1. indexing not prioritizing this kind of query and aligning it (which David Causse might know if that could be changed), essentially its metadata about Wikidata (it's available properties).

  2. it's 2.2 MB of data

I think that Yi Liu's Wikidata Property Explorer service then might want to instead cache the results for 24 hours for the best of both worlds.

To be fair, the raw amount of data requested seems to be approximately 2.2 MB and so probably should be locally cached by his tool for some determined time (like 24 hours).