This game is not your average click fest to begin with, and if you want to mod slow to be even slower... well, you can do that if you want, its easy enough (if a trifle time consuming). I wouldn't bother doing it myself.
It's not that hard, if you really want me to, i could put up a slower speed in about 5 or so minutes. All the settings do is apply modifiers to game speed, and they take about half a minute to change. However, ron is right, the game plays at the sedate pace many rts's seem to ignore in favor of jumping around like they forgot their last few doses of ritalin. You should really try the various settings before changing anything, because even on medium, a good player has a fair bit of time to admire the view.
EDIT: Here are the fun bits, from C:\Program Files\Stardock\TotalGaming\Sins of a Solar Empire\GameInfo\Gameplay.constants
gameSpeedData
taxIncomeGameSpeedScalar:Slow 0.0
taxIncomeGameSpeedScalar:Normal 0.20
taxIncomeGameSpeedScalar:Fast 0.40
resourceIncomeGameSpeedScalar:Slow 0.0
resourceIncomeGameSpeedScalar:Normal 0.0
resourceIncomeGameSpeedScalar:Fast 0.20
researchRateGameSpeedScalar:Slow 0.0
researchRateGameSpeedScalar:Normal 0.10
researchRateGameSpeedScalar:Fast 0.20
shipBuildRateGameSpeedScalar:Slow 0.0
shipBuildRateGameSpeedScalar:Normal 0.10
shipBuildRateGameSpeedScalar:Fast 0.20
moduleBuildRateGameSpeedScalar:Slow 0.0
moduleBuildRateGameSpeedScalar:Normal 0.10
moduleBuildRateGameSpeedScalar:Fast 0.20
shipLinearMaxSpeedGameSpeedScalar:Slow 0.0
shipLinearMaxSpeedGameSpeedScalar:Normal 0.30
shipLinearMaxSpeedGameSpeedScalar:Fast 0.5
shipLinearAccelerationGameSpeedScalar:Slow 0.0
shipLinearAccelerationGameSpeedScalar:Normal 0.15
shipLinearAccelerationGameSpeedScalar:Fast 0.25
shipLinearDecelerationGameSpeedScalar:Slow 0.0
shipLinearDecelerationGameSpeedScalar:Normal 0.60
shipLinearDecelerationGameSpeedScalar:Fast 1.0
cultureRateGameSpeedScalar:Slow 1.0
cultureRateGameSpeedScalar:Normal 1.0
cultureRateGameSpeedScalar:Fast 1.0
if you change these numbers downwards, and into negative numbers, be warned. You might get integer overflow and impossibly fast speeds. This tweak comes with the same warranty as forkbombs: if it breaks, you can keep both pieces. That said, it's using floats, not ints, so you should be fine just tweaking the slow numbers downwards. Still, do us all a favor and try the default settings to make sure they're too slow. If they are, this should be all you need.
