it looks like overclocking the pi using the "high" settings has resolved the issue.
it's currently playing the same 1080P MKV h264 file and hasn't stalled (yet) using rasplex.
scrubbing ahead also it almost instant.
it's currently playing the same 1080P MKV h264 file and hasn't stalled (yet) using rasplex.
scrubbing ahead also it almost instant.