Simplify model for performances?

I often use grabcad etc to get some great free models but sometimes the models are too detailed performancewise, ie if I download too high detail into a big scene everything becomes slow. I was wondering, does anyone know a good method to take a complex model and simplify it? Sometimes it works fine with just make2d, delete a bunch of lines then extract some stuff but I was hoping there could be an easier way. For example, opened this crane, it has 8373 meshes, 90,6k curves and it looks great, but for me it doesnt need to show the bolts, the screws etc, it just to resemble a crane.

Anyone know a good way to do this?

One display speed tip I like to use if there are lots and lots of mesh objects is to simply Join all the meshes into one mesh with the Join command. They don’t need to physically touch to become one mesh. This simplifies the number of objects Rhino needs to keep track of and makes the display faster. Also turn off mesh wires in the display mode of course.

Any luck?

Maybe I should but I usually dont work with meshes :(.

I now try to divide files instead and also just hide things I am not using while using some locked axis to have some reference.