Really slow QuickTime and Compressor conversions

Question

I have a FCP project that was shot in HDV and is about 35 minutes long. I need to output to Apple TV and to SD MPEG2 (to be used in DVDSP). Outputting in the formats I need is taking a really long time,much longer than I would think it should take.
As I'm one major rev down on Final Cut Studio, my version of Compressor doesn't have an Apple TV setting. I tried exporting to a QuickTime conversion for Apple TV, but for some reason it 'squashes' the picture into 4:3 format rather than maintaining 16:9. So I've had to resort to a two-step conversion process: 1) A QuickTime export at current (HDV) settings, and 2) Open the resulting movie in QT and do an Apple TV conversion from there. This preserves the 16:9 aspect ratio but takes a very long time (at least 4 minutes for each minute of HDV video). Also, the audio gets noticeably out-of-sync by the end of the video when doing the QT conversion.
My project is completely rendered inside of FCP, so I wouldn't think that the QT conversion would be so slow, but it is. After completing that I moved on to the SD conversion. In FCP I changed the 'easy setup' to standard NTSC settings, created a new sequence, and then dropped a copy of my HDV master sequence into the timeline of this new SD sequence. Rendering the video downscale from HDV to SD took about an hour.
Then I went to encode my now 35 minute SD sequence to MPEG 2 using Compressor. At the high quality 90 minute setting, it looked like the encoding was going to take 3 hours. I know from previous experience with straight SD video that this machine is capable of encoding a project of this length in realtime if not better (it's a Mac Pro with 4 cores and 5GB of RAM -- 35 minute of SD video normally would take no longer than 35 minutes to encode).
So, what's going on here? Is Compressor being fed unconverted HDV video from the source material rather than rendered SD video from the SD sequence? I also tried an export to QuickTime and it looked like that was going to take 2+ hours as well (just for a basic export of the already rendered SD video at current settings, not encoding to MPEG2).
Thanks in advance for any light you folks can shed on this subject, and any hints on ways to improve my export/encoding times.

Answer 1

The info about my system was out of date; I'd corrected it for my original post but forgot to on my followup. I've fixed it in my profile now so it shows my current system, which sounds very similar to yours.
And maybe I'm not explaining myself well enough. I'm not just talking about h.264 encodes from HDV, I'm also talking about extreme sluggishness creating a QT movie at regular NTSC settings that's already been converted from HDV to SD DV. How sluggish? Consider the following:
1) In FCP, I've got an NTSC SD sequence where I've copied in a 35 minute HDV sequence and already rendered the entire sequence at SD resolution. When I tell FCP to export a QT movie at DV NTSC 48Khz, the estimate begins at about 30 minutes and then quickly climbs to over an hour. I aborted after several minutes, with the time estimate still on the climb.
2) I created a new FCP project with the settings for NTSC SD. I located the the 'scratch' folder where FCP rendered the SD video I mentioned in attempt #1. I imported all the clips, verified that the movie is 35 minutes long and all expected footage is present, and then selected the exact same QT export option as in Step #1. The estimate started at 5 seconds and, sure enough, 5 seconds later it was done. I have a complete 35 minute long SD DV QuickTime movie sitting on my desktop.
So there's definitely something funny going on here. In both situations FCP should be using the same material -- the footage already converted to NTSC DV. FCP can create the QT movie in 5 seconds in one case (where the rendered DV footage has been imported) but will take ~ 2 hours in the other (doing the export from the sequence where the rendering to DV had been done).
I appear to have found a workaround -- import the rendered clips into a different project -- but am left wondering why this is necessary.