IMovie 11 slow and stuttering using Motion 5 clips

Question

Hi,
I'm using an 'old' 2008 Macbook Pro with 6GB Ram and a 2.5 Core 2 Duo.  Until now, everything has always worked with iMovie 11.
But now I'm trying something new:  I've retimed some .mov clips using Motion 5 --had no problem doing that-- and I 'shared' (rendered?) them using the default settings.  The files are larger than the original .mov files from the camera (original around 200MB,  retimed file around 700MB).  I put the files in the iMovie Events folder, started up iMovie and I can see and use the retimed clips just fine. 
However, for the first time, iMovie is really struggling very hard, the clips are stuttering and sometimes I have to wait for 2 or 3 seconds before playback continues (in the preview window, while editing in iMovie).
I've closed all unnessary applications and services, and all looks great in Activity Monitor, but still, iMovie editing is virtually impossible.
My question is :  will I be able to render the final movie without the stuttering, even though it's stuttering in the preview window?
Can I do something to get it faster while editing in iMovie?  Or did I do something wrong with rendering in Motion 5?
Or do I just need new hardware?
Many thanks,
Kris

Answer 1

hi,
if you are slow moing the footage then you could expect the resultant files to be bigger, since the clips are longer. However if they don't play well in iMovie, it could be that you have rendered them out with a codec that your computer cannot handle. Motion gives you a whole heap of codecs to render out to, and its even easier if you have Compressor. Have a look at one of the clips that you know does play nicely in iMovie. Open it in Quicktime player and then get the info window open about it. There it will tell you what kind of compression it has been rendered in, what the pixel dimensions are etc etc. You will want to try and copy those settings with your new clips out of Motion.
hth
adam