How to decipher CPU Lightmass Swarm's log ?

I have i7-14700K and 64Gb DDR5 RAM, and baking lighting for my outdoor scene (which relatively isn’t all that complex) with CPU Lightmass on Preview takes hours, while some people claim it should takes minutes.

Looking at Swarm’s log I can see that everything builds really quickly up to 99.2% and when “mappings” kick in, it takes ages for them to go from 99.2% to 100%.

I only have like 5 bounces for indirect and skylight, baked AO on and lightmap atlas is 512 (I dropped it down from 2048 in hopes to reduce lighting build times). Lightmaps rez on meshes ranges from 128 to 256 with only a handful of meshes having it set to 512.

Does anyone know what “mappings” are, in Swarm’s log legend? Maybe if I know what that is I can optimize scene to take less time to bake on my hardware?