fps too slow when using direct draw (WEC7 on i.MX53)

I'm using a freescale i.MX53 with all the freescale codec installed under WEC7.
I need to use an USB camera to viualize a video and to record a video.
I use the USB WebCam driver from codepkex ( http://cewebcam.codeplex.com/ ) compiled under WEC7.
When I try to visualize the video stream using DirectDraw all it's fine, but when I try to stast to record a video, The fps is around 3/5 Fps and the CPU usage rise up at 100%.
I notice that the IOCTL that take the buffer from the USB driver is called every 300 milliseconds.
If I try to call directly the IOCTL, I can read the buffer immediately, so it seems that the problem is between direct draw and the codec.

Any help is appeciated!

Beppe Platania Windows Embedded MVP http://blog.bepseng.it