Not terribly fast, I see a 1050AD OCC Diplo win, and there are probably faster too (especially on lower difficulties). Am still reasonably pleased with 1430AD though. Particularly because it was such a close call on several AIs just a few turns before the vote.
Hammurabi went Free Religion something like 2 turns before the vote, and thereby swung into my column. Couldn't do it myself because I'd lose several others if losing religious bonus. So many wars everywhere and worst enemy statuses, which made the diplo tricky. But as I already had -4 with Kublai (iirc that it was him), I took the chance to gift Asoka a pile of techs. The hope was to get +1 for sharing technologies. That didn't work. But I did get +1 for being a small civilization, presumably because he got catapulted to the top of the scoreboard. Phew! Mansa was iffy too, and he foolishly went FR a turn before I could gift him Economics, which precluded buying him into that for 5 turns.
However, in the end it did work out well
(Had built some spies to deal with the Hammi/Asoka situation, but thankfully it wasn't required)
Some of these OCC games have been nice, and I've been able to fill out a few more slots of the still very empty EQM table. It's nowhere near competitive with 'proper' games, but they sure are a lot faster.