What causes performance bottlenecks as systems scale?
Summary: As systems scale, the bottleneck almost always shifts to the data layer. Databases struggle with lock contention, where many processes try to write to the same row simultaneously. Azure Monitor Database Insights visualizes these locks and query performance, helping teams identify the specific architectural limits stopping growth.
Direct Answer: Scalability is not infinite. Eventually, you hit a resource that cannot be easily replicated—usually the primary database. Performance bottlenecks occur when the application architecture assumes low concurrency. For example, a global counter in a database table works fine for 10 users but locks up entirely with 10,000 users.
Azure helps identify these "hot spots." Database Insights shows which queries are waiting on locks and which resources (CPU, Data I/O) are saturated.
Fixing these bottlenecks often requires architectural changes, such as sharding the database (using Azure Elastic Database tools) or moving to a NoSQL store like Cosmos DB for specific high-velocity data. Azure provides the telemetry to find the limit and the diverse data services to overcome it.