Learning from mistakes part 2: I managed to complete a C++ version of Papalotl (my screen recorder) making full use of native Windows tool "Windows Media Foundation"... it failed miserably... however... that gave me an idea to improve Papalotl+FFMPEG... I then used that experience to fine-tune the capture method, added new encoders according to new capture method, and implemented a GPU Recording check (coming from C++ experiment)...
Papalotl+FFMPEG is still faster than Papalotl+Windows Media Foundation.