C:\Program Files\Stardock Games\Sins of a Solar Empire - Trinity\Diplomacy\GameInfo\Gameplay.constants
Inside that file you can see the different numbers used by the different game speeds.
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buildSpeedData-Slow
shipBuildRateGameSpeedScalar 0.0
moduleBuildRateGameSpeedScalar 0.0
buildSpeedData-Normal
shipBuildRateGameSpeedScalar 0.10
moduleBuildRateGameSpeedScalar 0.10
buildSpeedData-Fast
shipBuildRateGameSpeedScalar 0.20
moduleBuildRateGameSpeedScalar 0.20
buildSpeedData-Faster
shipBuildRateGameSpeedScalar 0.40
moduleBuildRateGameSpeedScalar 0.40
cultureSpeedData-Slow
cultureConnectionReferenceLength 250000
allegianceShiftRateScalar 0.75
cultureSpeedData-Normal
cultureConnectionReferenceLength 500000
allegianceShiftRateScalar 1.0
cultureSpeedData-Fast
cultureConnectionReferenceLength 750000
allegianceShiftRateScalar 1.25
cultureSpeedData-Faster
cultureConnectionReferenceLength 850000
allegianceShiftRateScalar 1.45
researchSpeedData-Slow
researchRateGameSpeedScalar -4.75
researchSpeedData-Normal
researchRateGameSpeedScalar -1.3
researchSpeedData-Fast
researchRateGameSpeedScalar -0.15
researchSpeedData-Faster
researchRateGameSpeedScalar -0.05
incomeSpeedData-Slow
incomeRateGameSpeedScalar 0.0
incomeSpeedData-Normal
incomeRateGameSpeedScalar 0.15
incomeSpeedData-Fast
incomeRateGameSpeedScalar 0.30
incomeSpeedData-Faster
incomeRateGameSpeedScalar 0.75
fleetSupplyData-Small
fleetSupplyScalar 0.75
fleetSupplyData-Normal
fleetSupplyScalar 1.0
fleetSupplyData-Large
fleetSupplyScalar 1.25
shipPhysicsSpeedData-Slow
shipLinearMaxSpeedGameSpeedScalar 0.0
shipLinearAccelerationGameSpeedScalar 0.0
shipLinearDecelerationGameSpeedScalar 0.0
shipPhysicsSpeedData-Normal
shipLinearMaxSpeedGameSpeedScalar 0.30
shipLinearAccelerationGameSpeedScalar 0.30
shipLinearDecelerationGameSpeedScalar 0.30
shipPhysicsSpeedData-Fast
shipLinearMaxSpeedGameSpeedScalar 0.45
shipLinearAccelerationGameSpeedScalar 0.45
shipLinearDecelerationGameSpeedScalar 0.45
shipPhysicsSpeedData-Faster
shipLinearMaxSpeedGameSpeedScalar 0.6
shipLinearAccelerationGameSpeedScalar 0.6
shipLinearDecelerationGameSpeedScalar 0.6
diplomaticPointsSpeedData-Slow
diplomaticPointsRateSpeedScalar 0.66
diplomaticPointsSpeedData-Normal
diplomaticPointsRateSpeedScalar 1.0
diplomaticPointsSpeedData-Fast
diplomaticPointsRateSpeedScalar 1.33
diplomaticPointsSpeedData-Faster
diplomaticPointsRateSpeedScalar 2.0
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Some of the numbers used are intuitive but others (researchRateGameSpeedScalar) aren't, unfortunately.