First of all, I'm not the creator, I'm simply posting a guide, and not involved whatsoever with its development.

Did you know there is an amazing Save Editor for Graveyard Keeper? It even works with any, all, or no DLC.

It is found at https://github.com/NetroScript/Graveyard-Keeper-Savefile-Editor

If you don't want to deal with installing python, please download the zip containing the executable:
https://github.com/NetroScript/Graveyard-Keeper-Savefile-Editor/releases/download/0.1.24/Graveyard.Keeper.Savefile.Editor.-.Windows.-.0.1.24.zip

Extract this wherever. Run the .exe (always scan even if you think its legitimate) and you will get a configuration popup, it asks for your save location, DLC to enable, and backup preferences. Your saves will likely be under C:\Users\YOURNAME\AppData\LocalLow\Lazy Bear Games\Graveyard Keeper.

As to why I stumbled onto this editor, I encountered a bug where my zombies refused to pick up at the quarry which resulted in unplayable lag from objects stacking continuously. The marble stacked all the way off the screen and not reachable or removable resulting in dramatic lag. This editor has a feature to DELETE ALL GROUND OBJECTS. I successfully fixed my game in this way.

To do this, open a save, scroll down to UTILITY, click it open, select remove all drops, and finally confirm. Then save your edited game file and start your game up. Enjoy the huge performance boost and potential bug fix.

It has many other features to use, I wouldn't suggest cheating but if you are replaying the game you could make your start slightly easier.

Thanks to the creator of the software, NetroScript