Weird Slowdowns.

[Tyestor]

Hello. I have a problem trying to playback some matroska files. This is puzzling for me as PMS usually works fine but lately it's just not working right. Basically, when trying to play an mkv file the audio slows down massively and the video becomes very choppy. This is weird as the mkvs I have tried so far are only 720p whereas I have had no problems playing 1080p video back previously. The files also play 100% perfectly on my PC so it definitely can't be the files. I noticed that enabling the "definitely disable subtitles" option helps somewhat but it is still unwatchable. Please help me =/

This is one of the videos in question:



CPU: Intel Corei5 2500k @ 3.8ghz
GPU: AMD (Gigabyte) HD6950 @ 840mhz/1350mhz
MoBo: Gigabyte GA-Z77X-D3H
RAM: G.Skill Ripjaws 12gb DDR3 1600mhz
OS: Windows 8 x64 Professional
Java: Java 7u7 x64

Playback files I currently use are as follows and are not up for replacement:

MPC-HC x84 JanWillem32 x86 AVX build.
MadVR.
MadFLAC.
xy-VSFilter.
LAV Filters.
Haali Media Splitter (mkv only).

This plays everything perfectly, including hi10p 1080p FLAC bluray encodes. I don't know why PMS is being so dodgy all of a sudden...

On a side note, is there any way I can use any of the above with PMS?

EDIT: Just managed to play back 1080p Hi10p AAC episode of Hellsing Ultimate. Wtf is going on, I should be able to play this fine.
EDIT 2: Just downloaded Serviio and the suspect files play perfectly fine there. The only problem is that serviio doesn't support .ass external subs or subs of any format inside a container (i.e MKV)....sigh. I need to know how to fix this. It's definitely something to do with PMS.