I have a Mac Pro with Dual 3GHz Quad-Core Xeon's, with 8GB 667 MHz DDR2 DIMM, an ATI Radeon X1900 512MB video card. I am running 10.5.5 with Final Cut Studio 2.
I am working on a heavily graphic project. It is :30 second kinetic typography project that has alot of graphics, animations, and moves. The computer is moving SLOWWWWWW!!!! I have had to cut the piece into 5 - 6 sec sections and export as a self contained movie. I am not able to do a RAM preview in realtime. When I Ram preview, the video lags enough to make the final export out of sync with the audio. I am at a point where I am exporting to QT just to check timing. This is unbearable.
I have deleted preferences, rebuilt preferences, all the "fixes" that is recommended on the COW. What am I missing? How do I get Motion 3 to work in realtime? I reduce the resolution to quarter while I work, but no help.
You need to do a little diagnosis first. Do you have iStat installed? (http://www.islayer.com/apps/istatmenus/) If not, add them, and turn on the options for CPU, Memory, and Sensors. Restart, then do a ram preview again, see if anything gets pegged. Make sure if you are using stills or video, that they are formatted to the size of your project. If Motion is needing to heavily scale your content, that's a lot of extra work.
Finally, you have a good, but 3 year old video card. If you work in Motion all day long, I'd get a Radeon 4870. You should see about 30% improvement (15 min renders become 10 mins) over your x1900. If you decide to sell it you could probably get about $125-$150 for it on eBay.