So I was wandering the surface looking for easy caves to explore and BAM, Crimson biome.
Now that I've discovered it, I'm a little worried about the area immediately to the left of it, since there are some nice caves I was planning to explore later on.
I haven't defeated Eye of Cthulhu yet, so I don't yet have the sunflowers to stop the spread of Crimson.
How much time (In-game and real time) do I have to stop the Crimson from spreading? How fast will it spread across a normal biome?