Longtime AutoCAD/Vectorworks/Revit user here, using both Win/MacOS and regularly get SHAPE files from clients. The main issue with Preview relative to files is that the document you're having issues with likely contains non-System (macOS) font files, including SHX characters, keeping in mind that your source CAD file may contain embedded fonts from your source template and linked/XREFed files. I get around these issues using one of 3 ways:
- Use only System fonts, while this is not my ideal solution sometimes the client demands it in our contract;
- Create my PDF documents from a DXF file;
- Before your export to a PDF file, check your output settings in the PC3 file of "DWG-to-PDF" - in the "Device and Settings" dialog, under "Custom Properties", in the "Font Handling" section, select "Capture All".
Adobe's apps - I use Acrobat DC, Illustrator, and PS - each use Adobe's Font Substitution engine. Skim and PDFPro don't do a very good job of font substitution. FWIW, some of the worst offenders I've worked with are agencies and their "creative" staff that work on mapping - the last document I received from one of my clients contained
35 non-system fonts and the documents were dogs, even in Acrobat DC and Illustrator on both Windows and MacOS; I used Illustrator to replace those fonts and re-send it to everyone on the distribution list - after "fixing" the fonts, the rendering was speedy for that 73MB file, even in Preview...
