Sounds like you might have more problems than just the second export time .... 2 to 3 hours to export from FCP doesn't sound normal at all. There are many variables that determine export time, including (but not limited to) the method used when exporting, the duration of the exported video, the codec of the exported video and of course, processor speed and system resources. But you've told us none of that so we'll have to guess.
Under normal circumstances, it shouldn't take 2 to 3 hours to export from FCP unless your Sequence wasn't rendered and/or you're using the "QuickTime Conversion" export method and/or the media in your Sequence isn't in a format that FCP works with natively. If you're going to use Compressor, the normal method would be to export a "QuickTime Movie" and make it self-contained or just a reference movie. Or you can just export to (or send to) Compressor.
As to why it's claiming 60 hours for the second export I really can't say ... but I've found that if you reboot the computer and then export, the time is greatly reduced. Why? I'm somewhat clueless as to why, but I assume the reboot clears out old swap files and system cache making the data flow faster.
Also note that you can speed up Compressor quite a bit by distributing the process among available cores.
-DH
