[0.16.36] Catching Up on high entity map

[Muppet9010]

When trying to join a 0.16.36 server in MP the Catching Up process can take a very long time to complete (20 minutes) on maps with very high entity (bitter) counts. While catching up my CPU usage is between 60% and 70% of Factorio usage with another 10% usage on other apps.
I can run a save of the map locally in SP at 60% CPU usage and with no UPS dropping.

I am running a dual core non-hyperthreading Pentium at 4GHz CPU and 8GB ram. During very high entity activity (mass bitter attacks triggered via artillery) Factorio can utilise close to 100% CPU, despite me being on an empty part of the map (graphically). Implying that the game and simulation can heavily utilise my pcs resources when there isn't much graphical load.

I am unsure why the CPU doesn't max out when trying to Catch Up as it does in other simulation situations. The issue was suffered by other players when trying to join this server and map.

Factorio Logs attached.
Save game attached.
Mods used attached.
Screenshot of the map running in Single Player mode with debug time usage attached while idle player activity.

I suspect active entities as the slowness as when other players antagonised bitters en mass, all players trying to catch up would start to have a negative catch up and those in-game would see FPS drops regardless of their location on the map. Then when the bitter waves were killed players who were joining started to positively catch up again (although slowly as before).

[Loewchen]

See: viewtopic.php?f=7&t=51319

[Muppet9010]

amended original post.