There is no way to make it faster other than a faster graphic chip (as it is fully done on GPU) or make the cells larger which likely isn’t an option if you opted it already (the cell should have the size of about the smallest occluded object)
Do you mean the part about the cell size?
For cells it does not make sense to have them smaller than the smallest dynamic object that will be occluded in the game, because the idea behind the cells is that you occupy as few cells as possible.
You can make the cells even larger but you will lose part of the optimization benefit as objects are detected as visible far earlier if the cells are much larger than the object itself.
I think the optimal cell size is somewhere between the size of the smallest object that is going to be occluded and 1.5 times its size