Should I get the same performance benefit from Firefox's DXVA implementation as a standalone player? It seems that no matter whether or not I have hardware acceleration enabled, watching an .mp4 video in Firefox uses the same amount of CPU (around 15%). If I save the video and watch it in a standalone player, I have almost 0% CPU used.
No, because streaming and reading from a local file are different reads and writes. Streaming is temporary cache and local file does not need http.
Well, I guess that makes a little sense, but even if I open the file locally and watch it using Firefox, I still get the same sort of performance.
There was also an update that addressed an issue with hardware accleration in 38.0.5.
However to further troubleshoot the cpu usage, we can try: