One important practice for optimizing Azure App Service performance is to enable application-level scaling. By setting certain thresholds, you can automatically increase or decrease the number of instances based on demand. Additionally, you can use features like Azure Traffic Manager and Azure Front Door for traffic distribution and load balancing. Another practice is to use Azure Application Gateway for SSL termination and HTTP routing, reducing the load on your backend servers. Finally, caching frequently accessed data using Azure Redis Cache can significantly enhance response times.

In order to optimize the performance of your Azure App Service, it is crucial to regularly monitor your application's resource utilization and performance metrics. You can leverage the Azure Application Insights service to gain insights into the performance bottlenecks and optimize accordingly. Additionally, take advantage of Azure Traffic Manager to distribute incoming traffic across multiple instances, improving scalability and availability. Lastly, consider using Azure Front Door as a global load balancer to route traffic to the closest and healthiest backend server.

The first thing you should consider is enabling autoscaling for your App Service plan, so that your application can handle varying levels of traffic without performance degradation. Additionally, you can optimize your code by using caching mechanisms like Redis or Azure Cache for Redis. Another recommended practice is to minimize unnecessary network calls and optimize database queries. Finally, consider using a Content Delivery Network (CDN) to improve the speed and availability of your static content.