During the struggle to get our project compressed after Compressor began refusing to ever finish a particular timeline, we learned something that might help.
Our computer is a Mac Pro with FOUR processors. It was pointed out that unless we had reset the "Instances" in Qmaster that Compressor would only be using ONE processor by default.
The number of Instances was reset to FOUR.
Increasing the Instances increased export speed of Quicktime files from FCP by about 50%. Unfortunately, this didn't help much when sending the problematic timeline directly to Compressor from FCP. It might have accelerated the compression, but only enough so Compressor dragged to a halt with nine or ten hours remaining instead of the forty—fifty hours before.
Making Quicktime movies is definitely considerably faster with FOUR processors cooking.
If you have a Mac with dual core processors, check to see how many are assigned to Compressor. The newer Macs have EIGHT processors. Increasing the number of processors assigned to Compressor might speed things up.
How to do it—
Go to System Preferences. Open Qmaster. Select Compressor. Click "Options for selected service" then reset the number of "Instances." Increase the "Instances" to the maximum and see if this helps.
In our case, increasing Instances didn't solve direct Compression from FCP, but there was a very noticeable speed up in making Quicktime movies.