I store all my content in H264 / AAC format for being the most compatible with my devices (Android and PS4) to avoid transcoding. But when the content has subtitles the transcoding always happens loading the CPU of the server unnecessarily (in my opinion).
It would be great if the players could use the graphic power they have to put the subtitle track on the video (like Kodi does, for example).
It is very sad not to be able to play a 1080P video on a PS4 because the server does not have enough power to include the forced subtitles, whereas if I remove the subtitles there is no problem.