VQ, AQ Buffer problems in large MKV files

[sq9mcs]

Hi

I'm newbie but i spend many hours with lot of OS in my RPi. I used raspbmc but it slower than xbian.

I make SD card (Kingston SDHC 10 class) with newest Alpha 5, and I have problems with large MKV files from my NAS. NAS is connecetd to RPi using NFS system. MKV files which have better than 30MB/s stopping from time to time. Always when VQ or AQ buffer are going down. I try to using Turbo mode but it didn't change it (XBMC work quite smoother). My LAN works in gigabit devices. Is there any possibility to change buffer size or another way to resolve that problem?

My RPi have 1.2A PS and I using HDMI (audio passthourgh)