I did set it to 6 GB and sadly to no avail, the error log is still the same.   

Took me a while to catch this on video, but here. Notice a big drop when zombie falls on the ground and then shuffles to face towards me, ingame FPS counter doesn't show it but steam FPS counter on top left does. Project Zomboid FPS drop.mp4

This feels similar to a discussion over reality vs gameplay mechanics I had a few years ago with how it was practically impossible to eat a little bait fish cooked while it was still hot because it would fade away before you could finish the eating animation, but for it to stay hot for 10 mins was "unrealistic".

It doesn't help hs_err_pid3988.log

Version: 42.19.0 Mode: Singleplayer Mods: [None] Save: None (Custom Sandbox UI before a save is created) Reproduction steps: 1. Go to start a Custom Sandbox game 2. Open the "World" tab 3. Tick "Advanced"