Sub titles freezes movie

So all my movies run fine until i select a sub title and it then it will freeze every 10 seconds. Any answers to why this may be?

What server?
What OS?
What client?
What subtitle type. e.g. SRT, ASS, VOBSUB, etc…

1080 mkv
Win 10 server
All client
SRT and vob.

I can only seem to run it in original format

It’s my opinion that subs have to be transcoded into the video, but i was just hoping for confirmation

If your subtitles are vob, then yes. Plex will transcode the file. I believe the only subtitle Plex can handle without transcoding is pain text SRT.

What Plex version do you have?