I just explained why his attack would be slower. Because it's a new game. The developers aren't going to have Ganon shooting full speed lightning every single game if they don't want him to.
Your one and only defense for this ball being lightning is that he shot lightning in OTHER GAMES. They did not, however, have him do it in THIS ONE. So, yes, by the looks of it, technically Ganon is a moron in OoT because he had better attacks, but he simply didn't use them. Why? Because the developers didn't have him use them. The developers don't have to give Ganon the same attacks in each game. It might be wise on their part to keep his abilities consistent, but THEY DON'T HAVE TO IF THEY DON'T WANT TO. So if you see an attack Ganon pulls out in a later game that is worse than stuff he did before, you cannot simply add states to power up the attack to where YOU think it should be.
Bottom line, there is NO indication time slows down, there is NO indication the ball is moving any faster than it is on the screen, there is NO indication it is anything other than a magic ball. Sure it cracks when it hits you. The effects placed on it look like electricity. Maybe the ball is electrical in nature. That doesn't mean it moves as fast as lightning. In Tails of Symphonia, you get a magic ring that shoots little balls of electricity. By your argument, since it sparks and zaps like electricity, it MUST me moving the speed of a bolt of lightning, right?
Of course not. This is a video game, things can, and do, work differently.
Also, Link has higher strength thanks to the gauntlets, but he himself is a normal guy. In fact, I'm pretty sure strength is the only thing he has higher than normal. He gets the Triforce, but it isn't clear exactly what that does for him.