Seems the science bug is not completely gone. I was able to create a temporary all 1 turn situation using 6 great scientists.
The reason I did the testing was that AI Korea suddenly researched 5 techs in 3 turns in a game without research agreements (or enlightenment era).
My test game, manipulated with IGE, no Firetuner.
VP 4.22, CvGameCore_Expansion2.dll fix applied, 4 unique components, IGE, really advanced setup, no other mods.
Start in industrial era. Korea, 1 city, science output 641. Has all sci buildings and sci wonders up to public school, 22 academy improvements.
All this within the same turn:
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Sci tree: Rifling 2 turns, archeology etc 2nd tier industry techs 3 turns.
Expend 1 g scientist.
Sci tree: Rifling 1 turn, 2nd tier industry techs 3 turns.
Expend 1 g scientist.
Sci tree: Rifling researched, 2nd tier industry techs 3 turns.
Don't choose a tech to research.
Expend 1 g scientist.
Sci tree: Archeology etc 2nd tier industry techs 2 turns.
Expend 1 g scientist.
Sci tree: Archeology etc 2nd tier industry techs 1 turn, biology etc 2 turns.
Expend 1 g scientist.
Sci tree: Everything up to information era 1 turn, inf era techs 2 turns.
Expend 1 g scientist.
Sci tree: All techs 1 turn, the cumulative numbers are weird:
arch 1, fert 1(-8), indust 1(-6), dyna 1(-3), milit sci 1(-1), bio 1(3), elect 1(7), corp 1(11), repl-par 1(15), comb 1(19), etc. For 10 techs listed here, all 1 turn, the cumulative prediction is 19 turns.
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From here I tried 2 different paths.
Path 1. Just keep clicking "next turn". 7 techs researched in 1 turn each. Now sci output is 797, corporations shows 2 turns to research and actually takes 2 turns. Research times show as follows: modern tier1 3 turns, modern t2 4, atomic t1 5, atomic t2 6, info t1 7, info t2 9, info t3 9, future 11.
Path 2. (Load the save where all techs were 1 turn). Delete all sci buildings and wonders, delete all tile improvements, reduce population. Science output falls from 641 to 64. 5 techs researched in 1 turn each. Now sci output is 83, biology shows 16 turns to research and actually takes >2 (didn't test whole 16). Research times show as follows: modern tier1 31 turns, modern t2 42, atomic t1 50, atomic t2 61, info t1 73, info t2 90, info t3 93, future 109.