I've got copies of the ISO standards for C99 and C++98, and ISO working drafts for C++11 and C++14, and they appear to be high quality (including a comprehensiv

I've got copies of the ISO standards for C99 and C++98, and ISO working drafts for C++11 and C++14, and they appear to be high quality (including a comprehensive TOC), but they've never exhibited the behavior you describe. That said, apparently one of my C++ working drafts actually causes Preview to spend 20+ seconds at 100% CPU when opening on macOS 10.12.2. That's no good, and I don't recall it doing this before. Time to go file a radar I guess.