Thanks for the advice.   That will work for a global config with lower input latency.   Additional Question Using the solution you proposed, can I create unique settings for each game system (NES, SNES, Megadrive), not only a global unique config?  Can I use your solution to create  NES configuration of threaded_video=false and another configuration with SNES threaded_video=true while inheriting retroarchcustom.cfg?