- Performance is how fast a system responds to a request.
- Scalability is how well a system handles increased load.
- Performance is about speed; scalability is about capacity.
- A system can be fast (high performance) but fail under high load (poor scalability).
- A scalable system can handle more users by adding resources (servers, databases).
- Improving performance means optimizing existing resources.
- Improving scalability often involves architectural changes.