[Home](./index.md) > [@firebase/performance](./performance.md) > [getPerformance](./performance.getperformance.md) ## getPerformance() function Returns a FirebasePerformance instance for the given app. Signature: ```typescript export declare function getPerformance(app?: FirebaseApp): FirebasePerformance; ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | app | [FirebaseApp](./app.firebaseapp.md) | The FirebaseApp to use. | Returns: [FirebasePerformance](./performance.firebaseperformance.md)