Speeding up preview Rendering in FCP 7

Hi All,

I have been working with a lot of 1080p HD video where I've been applying a bunch of color correction and filters to give the video a "film look" and to buff up some badly white-balanced video. Most commonly, I've been stacking two tracks of the same video, each with a Color 3-Way filter applied and composited with "overlay" or "add" or some amount of blending. Sometimes there will be one or two other filters applied as well, such as vignette or a gamma correction.

My problem is I've been finding the amount of time needed to render a "preview" of video every time I make a small change to this setup to be a drain on my workflow. For just 30 seconds or so of video, I must wait several minutes for a preview to render. I'm taking a lot of coffee breaks and things are progressing very slowly.

By "rendering" I mean renderding those segments of the video that are marked by the orange line- video which plays, albeit very jerkily. I am usually rendering to get a sense of the look of transitions, and the expressons of my subjects' faces at these moments- so I don't like the way the "orange line" preview look. I don't usally get the red line. Some of my blends that don't have color three-way applied are tagged green.

I have a Dual Core 2009 Mac Pro 2.66Ghz tower with 5GB of ram and the video card it came with. I'm using only one monitor. I have FCS 3 and FCP 7. I have tons of HD space available (200 GB out of 1 TB left on my main drive and a 2 TB scratch drive with about 800 GB used for TimeMachine and the rest partitioned for video. I'm not using it yet, though.) I usuallly run FCP with little or no other software in the background. The video source I'm using is HDV 1080p30 (shot at 1440x1080, but 16:9) or 1080p24 (some of my source video came from a second camera.) I have about 6 hours of video that I'm working with now, and have not, therefore, converted it to another format for editing purposes as this would take a long, long time. I set the render settings to RGB, which doesn't seem to speed things up much.

I'm looking for advice on how to speed up my preview render times (I'm not worried about compressor or QuickTime conversion render times as that can be done in batches overnight). Should I be choosing a different codec? Should I be rendering and editing at a different resolution (this seems to me to take even longer.) I'd be willing to spend a few hundred dollars for a new video card, if it came to that, but that's obviously my last recourse. Do I need more RAM? Are there some settings that I should change? Should I bite the bullet and convert my whole mess 'o video to ProRes 4:2:2 or something of the sort?

Any advice would be appreciated.