When I am watching content that does not require any transcoding, my PMS CPU usage goes up a little, around 10%, nothing drastic. However if I direct stream the content from a share from the same Server outside of Plex, my CPU usage does not go up. This is not a major issue however occasionally i get a few skipped frames when watching through PMS and not via a direct play.
https://support.plex.tv/hc/en-us/articles/200250387-Streaming-Media-Direct-Play-and-Direct-Stream
Direct Stream can also mean that the audio is transcoded, so cpu load can go up with Direct Stream, yes.
Please inspect the i under ‘Now Playing’ closer, to see what is exactly performed. It may give a clue.
https://support.plex.tv/hc/en-us/articles/200871837-Activity
Plex switches the Playback modes according to the information it has about the Plex client and which media formats it can Direct Play. This can and will differ if you compare it to playing the same file with e.g. Videolan Client.
To diagnose the issue further, please provide more information:
- the Plex client you use to playback
- technical information about the media file (mediainfo XML)
- the server version
- the hardware platform where Plex server runs on
