Contrary to what I'm reading here I think most of the pacing is quite ok, not every game needs to be beaten in a few hours. The prestige upgrades is the only thing I think needs a rebalance, a 15% boost doesn't feel meaningful enough for the time invested and also it gets more expensive...
I think this is just a matter of expanding the end game on the 3rd color giving us ways to earn more prestige points after reaching it, maybe add a merge item that boosts prestige amount by +1x? Or even +0,5x so it doesn't get too fast too quick? Or even something in the diamond upgrades after reaching green?