From the Department of Who Really Cares:
I did what I
think AlanH suggested (Thanks, AlanH!). I put the patched folder Civ III Complete in my Applications folder; and I put the RoC mod in my Documents/Civilization 3 Complete/Scenarios folder. It makes for a clean file structure. Or, at least, no messier than it ever has been.
I also did a fresh install and reconfiguration of C3C, so that I could directly compare how a game of RoC ran in the original and in the patched. I found out something interesting but useless: you can't take a game of RoC that was launched in one version of C3C and then load it in the other. If you try, you'll get a PediaIcon error message. Maybe that was foreseeable by folks smarter than me; just remember, I'm stupid enough to have
not backed up copies of my other mods.
Anyway, I'm inclined to agree with Empiremaker: The games I've launched and run with the patched version are slow and jittery enough that I think I'd rather just play the mods in the unpatched version with a reconfigured file and redundant file structure. But if anyone has any bright ideas on why some of us--but not others--are seeing a degradation in game performance under the patched version, I'd really like to hear them.
BTW, I've got an eMac that is souped enough that it's never had a problem running C3C before: 1 GHz PowerPC G4 w/ 1 GB SDRAM, running on OSX 10.4.7.
EDIT: Dojoboy, what AlanH said. The same thing happened to me, but it cleared itself up pretty quickly.