+1 on this.
From an analysis that we did last year, this fully connected discovery was also a major cause of RAM overhead.
We did some proof of concepts with fastrtps where we applied a whitelist: i.e. discovery was allowed only between entities that were matching in the whitelist.
Considering a 10 nodes system, RAM was reduced to almost 2/3.
I expect these numbers to not be accurate anymore as now with 1 participant per process the impact should be smaller.
However, given the advantages from many points of views (better discovery and performance) maybe is worth investigating again something similar?
@Jaime_Martin_Losa IIRC you had a branch with this feature, did this ever got into master?