Using FCPX 10.0.9, OS 10.8.5, MacBookPro thunderbolt, 8 gig ram, fast internal HD w 40% open space, mixed footage: one HDV, one iPhone, one Canon DSLR, all 1080i/24, plus a wav file off an H4N.
When I first boot up FCPX it plays back multi cam clips just fine. I can edit and play in real time all three clips. After about 15 minutes it begins to lag and only the first second plays smoothly when starting out, then it drops to a 1fps rate on both the source and record monitors. I can double click the multi clip in the bin and play it fine in 'edit' mode. I can view al three sources and the canvas monitors in real time. When I switch back to my timeline it is still at 1fps.
Everything is 1080i,24p, including the timelines.
It looks like a memory problem in FCPS. Any ideas on a solution?