Very cool. Took a similar approach to optimizing openutv by looking at flamegraphs. UTV is a fork of openrv which is an older release of the commercial RV. Like many things it uses ffmpeg and also native readers and writers for certain formats. Allowed me to get it to 8k@60fps buttery smooth playback with hardware acceleration. If you are still in the video/imaging space would love your feedback on UTV. openutv.com