when should we consider sharding our database? like, if its getting too big and slow, or there are other reasons?

Hey everyone, been hitting some performance bottlenecks lately with our main relational database. We're seeing query times creep up, and writes are starting to get bogged down as the dataset grows. We're already doing some basic indexing and tuning, but it feels like we're reaching a limit. Has anyone here gone through the process of sharding a relational database before? What were the key indicators that told you it was time to shard, and what were the biggest challenges you faced? Trying to figure out if we're at that point or if there are other optimizations we should exhaust first.