Optimizing config propagation time with target apps

Statsig has implemented an optimization to reduce config propagation latency, focusing on the time it takes for configuration changes to reflect in frontend or backend systems through their SDKs. This improvement centers around the use of "target apps," an advanced feature that manages which configurations are sent to specific SDK instances, enhancing performance and security by filtering out irrelevant configurations. By pre-filtering configurations based on their relevance to target apps, Statsig has improved Node.js event loop times, achieving a 66% reduction in config payload generation time for one of their major customers, thereby lowering latency and enhancing system responsiveness. The optimization involves an in-memory cache that maps configurations to target apps, ensuring only necessary configurations are included, which is crucial for companies with multiple apps and services. This advancement supports performance improvements by reducing memory usage and initialization times while enhancing security by preventing exposure of sensitive configurations.