In another case a customer received an AutoCAD drawing from a consultant. The drawing performance was very slow and crashed when he tried to edit it from a high-end CAD PC.
Taking a look at the side view of the drawing, one could see 3D objects, like chairs and other objects, appear. It is not very good practice to have 3D objects in 2D drawings, as lines drawn can snap to undesired 3D points and cause instabilities.
After trying to flatten the drawing, which ended weird results, the drawing was left with the 3d items.
It is only then I realised the drawing was placed in a GIS coordinated position, as the x and y coordinate of entities had large values.
After moving the drawing closer to the drawing origin of 0, 0, 0, the customer didn’t need the drawing to be coordinated. The unneeded items were deleted, as discussed in this article. I opened a new 2015 drawing using the ACADISO.DWT template and copied and pasted the remaining drawing entities into the clean file which performed much better.
It is always a good idea to Audit a drawing received from consultants and to check for 3D objects within the drawing. When you do find 3D objects, try to flatten them if possible. When a drawing starts to slow down, copy and paste it into a clean AutoCAD drawing, ensuring you move it as close to 0,0,0 as possible.