This mod looks interesting... but before I use so much of my cap downloading it, I must know... what are the turn times like? If it's as bad as RoM/AND, then I'll have to say no... I can't see how it wouldn't be.
QUICK ANSWER
On turn 663 out of 1625 (2511 BC @ Marathon speed) Gigantic ROM_Terra, 24 civs, it takes 35 seconds between turns. My PC has a WinExp rating of 5.7
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First my machine. It's a Intel dual core 3.0GHz with 8G memory running Vista Ultimate 64 bit. The graphics card is NVIDIA GeForce 9800T w/ 512M memory. My Windows Experience Rating is 5.7. If you have Vista or Win 7 then the Windows Experience Rating is the best benchmark.
Now my game settings. I play on Gigantic ROM_Terra maps at Marathon speed. You will need a 64 bit O/S with 8G memory to run this mod
IF you like to play on Gigantic maps. Loading all those new buildings, tech, units, graphics, religions, etc. takes memory, and lots of it. You can't have too much memory if you want to SuperSize your Civ experience, especially the modpacks that load lots of new objects.
Loading the game takes about 2 minutes when you first launch the application. If you run Windows Task Manager and add a column PF Deltas (Page Faults) on the Process tab, you'll see that the Civ3 process is thrashing the disk. That's all the reading of XML files and buidling memory objects. Play a game of Freecell while you wait.
Now (finally!) for the answer you're looking for. I'm on turn 663 and there are 23 other Civs and about 50 odd cities on the map. (the other Civs are slow to expand w/ this mod). I'm on turn 663 out of 1,620 turns, roughly 2500 BC. It takes 35 seconds from when I click End Turn to when I free to do something.
So look at your PC and map size and speed and adjust from there.
Since the mod is based on RoM/AND and you don't like the turn time for that mod, you probably won't be satisified with this mod's turn time.
Despite that, consider downloading it and playing the Pre-historic era. It's a very different game experience from what you're used to. The animal hunting and capture is very unique. Create a small map and a quicker speed and see how you go.
I also have a capped ISP and do the downloads in non-peak hours. See if your ISP gives additional limits for non-peak use.