I'm not seeing any crashes or slow down but only do edits with no effects. Do you have any effects or are you forcing any parameters in clip properties that may be a reason for slowdown? Maybe a bug in MLT or ffmpeg/libav has appeared?

No effects. But the rendering is very very slow. Didnt crashed lately but it takes lots of time to render any time of format. Even if I have 8 cores and use all of them. Am not sure if is taking advantage of my ATI video card.