How to manage big scenes in blender

Hello, i face constantly a lot of slow downs while using blender with huge scenes, lots of objects and lots of geometry (20 million faces a scene for example).

The slow downs are the following:
-the time to do a ctrl-z is painfully slow
-the time to pop up a layer containing important assets is slow.
-the time to go from object mode to edit mode is really slow.
-selecting in edit mode is incredibly slow with high poly meshes, starting to 1millions faces.
-loading the rendered view Or pre rendering a render take at least 5minutes.

Here is a few tips to avoid those issues that I found by myself, but please if you have any more to add to the list, or link to solutions, tell me, it will help me, because even all thoses below my scenes are still really slow, and every people who do research for this subject.

Solutions:

  1. Are ou sure that every asset when needed are instanced? Both material and meshes?
  2. Use collection/layer to disperse every meshes to different groups.
  3. use simplify to Reduce résolution of texture in the viewport, amount of subdivision, max child particle amount.
  4. of there is a particle system, are they displayed at 100% viewport visibility ?
  5. … ?

Blender guru has a few helpful tips in this tutorial for speeding up the process. Even though he’s working on a low asset scene, it should still be useful to follow his guidelines for when a scene gets intense. For example, using flat planes with a tree texture to fill the background.

Turning on Bounding Boxes for objects that do not require visual representation should help.

If you can use instancing (linked duplicates) as much as possible.