ClickHouse is a complex piece of software that introduces new concepts to users, leading to common issues such as "Too many parts" due to poorly chosen partitioning keys or excessive materialized views, which can slow down inserts. Users should also be aware of the limitations of primary key selection, overuse of data skipping indices, and the behavior of LIMIT clauses in queries. Additionally, ClickHouse has features like memory overcommit capabilities that allow more memory-intensive queries to run when server resources are available, but require careful tuning at a server and user level. Users should also be cautious when using experimental features, as they may not be production-ready or may introduce risks. Overall, managing a ClickHouse cluster in production requires attention to these common pitfalls to avoid performance issues and ensure the speed and power of the software.