And yet, FFmpeg couldn't really have been written in anything else. A 5% difference in performance could be the difference between a 1080p video decoding in real time on a low powered device like a phone or a netbook and the video decoding slightly slower than real time. Improvements to FFmpeg made my old netbook work as a video player. I don't think I would have been able to use an FFmpeg-based player at all if it had the overhead of being written in a more memory safe language.