Why is it so slow and so difficult to get through this?

“The path to Allaah is long and we pass along it like turtles. The goal is not that we arrive to the end of the path. Rather, the goal is that we die while we are on the (straight) path” (Shaykh Muhammad Naasir-ud-Deen al-Albaanee)

Every single stage of our path to Allaah, of our journey of belief, holds its own perfection, its own specific meaning for us, and will facilitate something that is yet to come. Each stage is both required for the next, and perfect for that moment . Each stage is both temporary, and where we need to be.