I think the heavier elements exponentially speed up stellar death. In part, the fusion of elements makes the core denser and denser each step of the way. Going from hydrogen to helium is twice as dense, but helium is still a good fuel so it isn’t an issue. As fusion continues through carbon and oxygen, it shrinks but still burns. Iron is the tipping point though because it doesn’t work as a fuel at all - it triggers a core collapse, the surface falls into the void, and everything heavier than iron is instantaneously fused and thrown into the universe.
So I would guess the lesser abundance of heavier elements early on delayed that process compared to today’s standards. Sort of like making a snowman in fresh powder and having to melt/wet the snow to make it pack vs having a little rain and higher temps after the powder to wet it