Find and diagnose performance issues with Azure Application Insights

Azure Application Insights collects telemetry from your application to help analyze its operation and performance. You can use this information to identify problems that may be occurring or to identify improvements to the application that would most impact users. This tutorial takes you through the process of analyzing the performance of both the server components of your application and the perspective of the client. You learn how to:

  • Identify the performance of server-side operations
  • Analyze server operations to determine the root cause of slow performance
  • Identify slowest client-side operations
  • Analyze details of page views using query language


To complete this tutorial:

Log in to Azure

Log in to the Azure portal at

Identify slow server operations

Application Insights collects performance details for the different operations in your application. By identifying those operations with the longest duration, you can diagnose potential problems or best target your ongoing development to improve the overall performance of the application.

  1. Select Application Insights and then select your subscription.
  2. To open the Performance panel either select Performance under the Investigate menu or click the Server Response Time graph.


  3. The Performance panel shows the count and average duration of each operation for the application. You can use this information to identify those operations that most impact users. In this example, the GET Customers/Details and GET Home/Index are likely candidates to investigate because of their relatively high duration and number of calls. Other operations may have a higher duration but were rarely called, so the effect of their improvement would be minimal.

    Performance panel

  4. The graph currently shows the average duration of all operations over time. Add the operations that you're interested in by pinning them to the graph. This shows that there are some peaks worth investigating. Isolate this further by reducing the time window of the graph.

    Pin operations

  5. Click an operation to view its performance panel on the right. This shows the distribution of durations for different requests. Users typically notice slow performance at about half a second, so reduce the window to requests over 500 milliseconds.

    Duration distribution

  6. In this example, you can see that a significant number of requests are taking over a second to process. You can see the details of this operation by clicking on Operation details.

    Operation details


    Enable the "Unified details: E2E Transaction Diagnostics" preview experience to see all related server-side telemetry like requests, dependencies, exceptions, traces, events etc. in a single full screen view.

    With the preview enabled, you can see the time spent in dependency calls, along with any failures or exceptions in a unified experience. For cross-component transactions, the Gantt chart along with the details pane can help you quickly diagnose the root-cause component, dependency or exception. You can expand the bottom section to see time-sequence of any traces or events collected for the selected component-operation. Learn more about the new experience

    Transaction diagnostics

  7. The information that you've gathered so far only confirms that there is slow performance, but it does little to get to the root cause. The Profiler helps with this by showing the actual code that ran for the operation and the time required for each step. Some operations may not have a trace since the profiler runs periodically. Over time, more operations should have traces. To start the profiler for the operation, click Profiler traces.

  8. The trace shows the individual events for each operation so you can diagnose the root cause for the duration of the overall operation. Click one of the top examples, which have the longest duration.
  9. Click Show Hot Path to highlight the specific path of events that most contribute to the total duration of the operation. In this example, you can see that the slowest call is from FabrikamFiberAzureStorage.GetStorageTableData method. The part that takes most time is the CloudTable.CreateIfNotExist method. If this line of code is executed every time the function gets called, unnecessary network call and CPU resource will be consumed. The best way to fix your code is to put this line in some startup method that only executes once.

    Profiler details

  10. The Performance Tip at the top of the screen supports the assessment that the excessive duration is due to waiting. Click the waiting link for documentation on interpreting the different types of events.

    Performance tip

  11. For further analysis, you can click Download .etl trace to download the trace in to Visual Studio.

Use analytics data for server

Application Insights Analytics provides a rich query language that allows you to analyze all data collected by Application Insights. You can use this to perform deep analysis on request and performance data.

  1. Return to the operation detail panel and click the Analytics button.

    Analytics button

  2. Application Insights Analytics opens with a query for each of the views in the panel. You can run these queries as they are or modify them for your requirements. The first query shows the duration for this operation over time.


Identify slow client operations

In addition to identifying server processes to optimize, Application Insights can analyze the perspective of client browsers. This can help you identify potential improvements to client components and even identify issues with different browsers or different locations.

  1. Select Browser under Investigate to open the browser summary. This provides a visual summary of various telemetries of your application from the perspective of the browser.

    Browser summary

  2. Scroll down to What are my slowest pages?. This shows a list of the pages in your application that have taken the longest time for clients to load. You can use this information to prioritize those pages that have the most significant impact on the user.

  3. Click one of the pages to open the Page view panel. In the example, the /FabrikamProd page is showing an excessive average duration. The Page view panel provides details about this page including a breakdown of different duration ranges.

    Page view

  4. Click the highest duration to inspect details of these requests. Then click the individual request to view details of the client requesting the page including the type of browser and its location. This information can assist you in determining whether there are performance issues related to particular types of clients.

    Request details

Use analytics data for client

Like the data collected for server performance, Application Insights makes all client data available for deep analysis using Analytics.

  1. Return to the browser summary and click the Analytics icon.

    Analytics icon

  2. Application Insights Analytics opens with a query for each of the views in the panel. The first query shows the duration for different page views over time.


  3. Smart Diagnostics is a feature of Application Insights Analytics that identifies unique patterns in the data. When you click the Smart Diagnostics dot in the line chart, the same query is run without the records that caused the anomaly. Details of those records are shown in the comment section of the query so you can identify the properties of those page views that are causing the excessive duration.

    Smart Diagnostics

Next steps

Now that you've learned how to identify run-time exceptions, advance to the next tutorial to learn how to create alerts in response to failures.