Darwinian theory predates all genetics - as Darwin well knew, he had no mechanism.
That's one reason he piled up the data and correlations for so long, in big thick books full of detailed and multifaceted correlations from widely disparate taxonomic categories of living beings - without a mechanism he needed a strong, dense, painstakingly documented base of circumstantial evidence.
The upside is that he did build one, and by necessity it was good for almost any mechanism - when the genome was discovered it slotted right in. So does epigenetics - another way to provide the heritable variation and conservative stability that is all Darwinian theory requires of its reproductive mechanism.
Darwinian evolution does not have to be slow. It just happens to be, in normal circumstances, for multicellular animals especially.