0.000 2019-03-14 22:18:32; Factorio 0.17.12 (build 43667, linux64, alpha)
0.036 Operating system: Linux (Ubuntu 18.04)
0.036 Program arguments: "/home/will/bin/factorio/bin/x64/factorio"
0.036 Read data path: /home/will/bin/factorio/data
0.036 Write data path: /home/will/bin/factorio [405540 ...

Thanks for the report,

However this isn't really a bug, you are making the game do a lot of work by aggro-ing many biters, so a slow in game performance is quite expected

Wasn't 100% sure if this counted, feel free to WONTFIX. As mentioned after killing all biters performance is restored.

What ...

After a bit of searching I found the following command to remove all mobile enemies: `/c game.forces["enemy"].kill_all_units()`. After running this i'm back up to 60 UPS.

I've got a slowdown with a high entity update count (~50). I'm playing with the aircraft mod, the slowdown started after annoying many biters. Depending on where I am the UPS is between 10 and 20.