Hi there.

I'm still fairly new to editing but as I try to play back my project, the project monitor becomes very slow through transitions - Particularly composite.
The behaviour is identical to http://www.youtube.com/watch?v=jemvS942IJY, (though that's not my video).

I'm running...
kdenlive 0.9.2
Fedora 17
mlt-0.7.8 (I think. It's the most recent Fedora version from the repos/rpmfusion but I'm not able to check right now)
Hardware is quad core i7 2.2GHz, 8GB RAM, Nvidia GT550M (Nouveau).

If anyone is able to help me with this it would be greatly appreciated!

You may want to use proxy clips which will allow you better performance. The hardware, escpecially the video card does not help you in this case.

You could try "Real time (drop frames)" from the right click menu on the project monitor.

Setting this to the Checked state means the clip monitor will drop frames durring playback to ensure the clip plays in real time. This does not effect the final rendered file - it just effect how the clip appears when being previewed in the clip monitor

http://userbase.kde.org/Kdenlive/Manual/Monitors/Project_Monitor_RightClick#Real_time_.28drop_frames.29

Thank you both for your replies. Al25fps, I was already using proxy clips which was why I was a bit perplexed! I thought my specs weren't too bad for a laptop!
Ttguy, thank you very much for the tip. I will give it a go!

EDIT: Disappointed to find I already had this option selected. The slow down still occurs. Tried without the tick box selected and the effects were far worse but that doesn't make the original right! :(

Hmmm... too bad. Hope mlt 0.8.2 (the most recent version available for Archlinux) helps and will be available for you, soon.