All the setting is the same except the FPS, by just changing the FPS alone seem to have cause the bit rate to be unstable? I have test at (60/30/25). CPU percentage seem low, so i'm not sure what's wrong. Looking to be educated here and if you more data from me feel free to let me know.
Log : https://hastebin.com/itizamoriq
Log : https://hastebin.com/itizamoriq