When loading the asset editor, workshop assets can slow down the loading time and some mods may cause problems as they are not meant for the asset editor. It's possible to load the game without workshop content, and you can still use workshop assets and mods by adding them locally.
Create shortcut window.
It's possible to run no workshop mode by using a steam parameter, but adding or removing it every time you want to enable or disable workshop takes time, so creating a separate shortcut for no workshop mode is more efficient.
Right-click in any folder or the desktop and click on New > Shortcut. Click browse and navigate to the steam executable, which is usually located here: C:\Program Files (x86)\Steam\Steam.exe and at the end of the path add this: -applaunch 255710 --noWorkshop
This shortcut can now be used to launch the game in no workshop mode.
Local Mods & Assets
In no workshop mode, only local mods and assets are loaded. But it is still possible to use workshop content by copying the files from the workshop folder to the local mods and assets folders.
The workshop content is located here:
C:\Program Files (x86)\Steam\steamapps\workshop\content\255710
and the folder name matches the id seen in the workshop item URL.
You can copy mod and asset folders to the corresponding local folders located here:
The AppData folder is hidden by default, you can access it by pressing Windows + R and typing in appdata.