Proxy Geometry Nodes
Proxy Geometry Nodes is a node for geometry nodes that helps to preview a large number of objects instantiated in geometry nodes, allowing a light preview in the viewport, but allowing to see the original object in the render.
I hope you find it useful, I made this node for my personal projects and it is quite tested for at least a few weeks of work.
To use it, you must add the Nodetree Proxy to your blender from the file you download.
Select 1 of the objects that you will use in your Geometry nodes scatter, add a new Geometry nodes, assign from Group the Proxy node and that's all, then to each element that you want to instantiate you must assign the same geometry nodes of the first one, this way all the objects will be changed from only 1 node, you can still leave them separately.