You're not running into issues with building the N64 emulator mupen64plus? It's only happening on Debian Stretch (x86-64) but it could be my setup so that's why I'm asking. It's requiring a newer version of cmake than what's available:
/home/pi/RetroPie-Setup/tmp/build/mupen64plus/GLideN64/projects/cmake /home/pi/RetroPie-Setup/tmp/build/mupen64plus /home/pi/RetroPie-Setup
CMake Error at CMakeLists.txt:1 (cmake_minimum_required):
CMake 3.9 or higher is required. You are running version 3.7.2
Awesome! I set up open box to start with 1280x720, verified it via the log, and it worked perfectly with the threading set false. Looks way better than it did set true, has better response/less lag, and of course the screensaver doesn't kill it after 10 minutes.