Having played this for about 50 turns, I think my initial reaction is Whoa! that is fast!
I certainly feel like the banilla marathon speed game is too slow, units take too long, many buildings take too long and city growth is too slow. However, I do not think that science and wonders are too slow in vanilla (perhaps a tad bit slow for both, but nothing more than 5% max).
It appears that all time dependent in game process have been sped up by a factor of 3 or 4. I'm seeing AI civs with 3 or 4 cities within 30 or 40 turns. Wars are breaking out within 20 turns, and wonders like Artemis, Zeus and Pyramids are already being built before 3500 BC.
Here would be my suggestion:
1. Units keep them about as fast as they are, but not quite so fast. If the current rate of production for units is U, then I'd say make it 0.9U.
2. Buildings also not too much change, but a bit more than units B for current (modded) building rate, I'd say change it to 0.82B.
3. City growth. Right now it feels like it is about three to four times faster than vanilla marathon speed. I'd say it should only about 1.5x faster than vanilla marathon. That will also reduce science and technology gains somewhat.
4. Wonders, leave them almost as slow as in marathon vanilla. If M is the Marathon vanilla rate of Wonderbuilding, change it to maybe M0.91
5. Science, meaning completion of techs, is way too fast. I had an AI civ (this was on Hard difficulty, Terra, Huge, 17 AI, 30 or so CS, and temperate legendary start) I had AI Civ building the Pyramids, Statue of Zeus, and Artemis before about 3750 BC and someone entered the Classical Era at about 3700BC. Making changes to city growth may slow down the science a bit, so it might be good to test it with the city growht changes and see what other changes need to be made to techs.
I totally understand wanting to change game parameters so that it is possible to build a fairly large number of units during just one era, and also to be able to build most of the era buildings and get some real benefit of them before they become obsolete. Basically speed up acquistion of units, and slightly less buildings.
However, right now, even the units and buildings are a tad bit too quick, and the pop growth (and related science) and Wonder building are WAAAYY too fast. With AI ripping through the tech tree and building Wonders that fast you'll wind up having modern warfare with scores of units on both sides by around 10 AD!
I'll have a look at your files but if you can point me to the parameters that are shaping