They are slow until you receive your initial email from the HR. It took me about I can't even remember how long, like 2-4 months after submitting my application. Once the interview process starts, the process is pretty quick. You don't hear back if you don't move onto the next round.

I had three separate interviews for the Curatorial Assistant position. They were spaced far apart, the whole process took more than four months for the museum to ultimately tell me they moved forward with another candidate. Everyone I interviewed with was incredibly nice, but asked tough questions.