I have a map (exported from some GIS-program) to a PDF with several thousands sublayers. The problem is that the simplified map layers on top of the layers hierarchy are probably just a smaller proportion of the total number of layers. So I am trying to simplify the document in order to delete the various layers that are not visible. The problem is that the document is really slow (Using a fairly proper basic HP Z workstation with a Quadro card) so I'd like to get some clues how to fast select and delete perhaps 100-500 sublayers at once?
As Scott pointed out, there's a difference between selecting layers and selecting objects. Selecting layers takes up almost no resources, whereas selecting objects does.
In the example below, I've only selected the layer, not the object inside it:
And in the following example I've selected the objects in the layer (notice the blue square and the highlight on the artboard):
The key to deleting layers without you computer grinding to a halt is thus: select only layers (batch select them with ctrl or shift), then delete them by dragging them to the bin: