Movies freeze few seconds

Hi
I just install OpenPHT on the same system than the Plex Server (Core I3/Linux Mint) and sometimes when I played movie, the image freezes few seconds (the sound continue goes on).
It could appears many times during the movie playing.

When I check log files, I could find this message: “WARNING: CRenderMessage: WaitForBuffer - timeout waiting for buffer”, is there a link between my problem and this message?

Have you a solution for this kind of problem?
Regards

What is your setup (server, network, player device, etc.)? Also, does this happen with every video file?

Same system for the server (v1.11) and the player (OpenPHT 1.8) on Linux Mint 18.3 with a core i3 6100 and 8GB.
It’s played locally.

And yes it’s seems that it appears for each movie (1080p). It’s seems too that CPU usage for OpenPHT is very hight (~ 50-60%)