So, when should you think about breaking up a big, monolithic application?

i've been working with a pretty big monolith for a while, and we're hitting some performance and dev speed bottlenecks. we're not at the point where we *need* to break it up, but i'm starting to think about when the *right* time to start planning that might be. it feels like there's a tipping point where the complexity of managing the monolith starts to outweigh the benefits of a single deployment. what are your signals for when it's time to seriously consider moving to microservices, rather than just waiting until it's a crisis?