In addition to more horsepower, you can do other things that help to speed up your work in LO.
Start in SketchUp first. Make sure you are using layers (properly) to control the visibility of entities in the scenes you create for the viewports. Turn off layers for entities that aren’t visible in the scene anyway.
If you want to use sketchy or other styles, don’t apply them initially. Use a fast style to start with . These are identified by a little green clock icon on their thumbnails. After you have your viewports positioned and the model is set, change the style for the scenes in SketchUp and update the reference in LayOut.
Don’t display materials while working. The slow down the rendering.
Purge unused stuff from your SketchUp file and keep it clean.
In LayOut, make sure you are keeping the viewports connected to the scenes. Don’t allow them to become modified.
Make sure you a single reference listed to each SketchUp file you use. This means no dragging and dropping from SketchUp to LayOut.
Usually plain old raster rendering is faster but Vector rendering doesn’t show textures so it might be better for you. Change the rendering style to Hybrid toward the end if you need to show textures (but not sketchy edges)
There are some other things you can do but these should get you started.