The following graphs show the `perf` results from creating 1'000'000 item stacks in minetest using various constructor forms.

ItemStack()


            for _ = 1,1000000 do
              ItemStack()
            end

ItemStack(itemstring)


            for _ = 1,1000000 do
              ItemStack("mod:item 1")
            end

ItemStack(table)


            for _ = 1,1000000 do
              ItemStack({
                name = "mod:item",
                count = 1,
                wear = 50,
              })
            end

ItemStack(itemstack)


            itemstack = ItemStack({
              name = "mod:item",
              count = 1,
              wear = 50,
            })
            
            for _ = 1,1000000 do
              ItemStack(itemstack)
            end