When should you think about getting a separate analytics database?

Hey everyone, I've been thinking about our current setup. Running all our analytical queries straight against our production transactional database is starting to cause performance hiccups during busy times. I'm considering setting up a separate read replica, or maybe even a dedicated analytics database, you know, like a columnar store. What's your experience with this? When did you actually make the switch? What were the biggest challenges and benefits you noticed? I'm really looking for practical advice on when this just becomes necessary, not just something that's nice to have.