Versions:
NeoForge 1.20.1-47.1.104
ars_nouveau-1.20.1-4.10.0-all

Replication:

1. Create ~1.5k ars lights, as players will do
2. run observable,
3. check aggregates, example
   https://observable.tas.sh/p/X1LI/aggregated

Spark shows something about a light tile, but the tick is negligible. Going to close. Guess at least this is documented here in case someone else sees it on their profile.

Run a spark profile, Observable is known to misappropriate lag. The LightBlocks only tick on clients.