Sudden slow down in rendering FSCPX
 

I have been using FCP 6.5 for about 3 years and I am making the transition to FCPX over the last 2 months. I am running it on a 24" imac (iMac8, 1) with 4 gig of ram under Snow Leopard. Whilst 6.5 ran well with the computer I know that I am probably pushing it with FCPX , still, except for one problem which I will get to, it has run remarkably well so far.

My problem is that during a render the render will suddenly slow down to 1/10 th the original render rate. I can't pin this slowdown to any particular action at the moment. To cure the problem I have to trash the preferences and restart the computer which is a real pain as it can happen a number of times during a session. Has anyone had this happen to them, and is there any cure?

All suggestions wellcome

Ian