The speed at which science advances depends on many factors: single player difficulty level, multiplayer, map, style of play, etc.

In some games science gets well ahead of historical.
For example Tanks could be invented in the 1700s rather than the 1910s.

Some players may find the average rate of science advancement in the games they typically play is not ideal for their enjoyment.

Thus it would be good to allow an option to adjust the science speed when you customize the game, similar to the other current player options at the start of the game.

There could be several speeds such as: normal, slow, slower, slowest, fast, faster, fastest.

It could be programmed by multiplying the cost for researching technologies by an appropriate factor.
I suspect it would work best if the factors varied by era, with no adjustment for the first era, a modest adjustment for the next era, a bigger adjustment for the next era, etc.
It might also be necessary when you decrease (increase) the science speed to increase (decrease) somewhat the benefit for knowing other civizilations who already have the given tech.
(I assume this benefit is still a feature.)