Matlab VideoWriter Disklogger - Too slow for HD - performance

Question

I am trying to capture a video with matlab.
The Video might have a duration of about 15-60 minutes, so it is pretty big and I store it to disk instead of memory. (I don't need online precessing)
I want to capture the video in high resolution (1280x720 would be fine). But with High Resolution, I get the problem, that Matlab does not log the data fast enough to the disk.
Here are my observations:
Resolution of 640x480: Everything works fine.
Resolution of 800x600 or above: The utilization of my RAM increases linearly, while capturing the video and decreases linearly after i stop capturing the video. After the stop command, Matlabs Command Window is blocked for some time. While that time, I can see tat the .avi - file is growing. Of course, the higher I pick the resolution, the faster the RAM utilization increases.
So my problem is, that I cannot use a Resolution of 1280x720, because after caputring the video for about 5 minutes, my whole RAM (8GB) is utilized and I get an awful out of memory error. (Interesing fact: the video that uses my whole RAM has only about 300 MB. That must be the MJPEG compression rate)
Has anybody got an idea how to solve my problem? Is matlabs VideoWriter class just too slow and there is nothing I can do? Other softwares for video capturing are also able to make HD Videos..
Best regards,
Richi
For the completeness, here is the code that i used:
path = 'C:\Daten\test\test.avi';
videoRec = videoinput('winvideo',1,'MJPG_1280x720');
src = getselectedsource(videoRec);
src.FrameRate = '30.0000';
set(videoRec,'TriggerRepeat',inf);
set(videoRec, 'LoggingMode', 'disk');
logger = VideoWriter(path);
set(logger,'FrameRate',str2double(src.FrameRate));
videoRec.Disklogger = logger;
start(videoRec);