How to optimize drafting in Rhino from imported CAD

hi guys, perhaps a common question, but i have these problems:

  1. I imported CAD files to Rhino. the cad files consist of full construction drawing of a shopping center. (20 Mb size in CAD). i know that in CAD, i can move around and navigate without lagging because CAD is more optimized for 2D.

  2. when openning in Rhino. it becomes very slow and whenever i pan around takes few second to do so.

  3. i can try to organize them in specific layers, by hiding or unhiding them whenever i need it.

but is there away in the setting to optimize viewport when navigating? (for example like when panning, automatically draw complicated lines as bounding boxes without having to go through properties for each?) like CAD when the files is big, when panning around, the software automatically creates bounding box so that it saves computer power for drawing on the viewport.

thank you so much ^^ sorry noob question

edit: it gets worse when trying to select the objects, and changing layer properties for example. for these 1 million curves

Mr. Yang,

Make sure you are in wireframe.

Try turning off Dimensions and Text using the Edit>Select Objects commands.

Continue to isolate as much as you can and put on layers with the visibility turned off.