Solving the Blazor Server App Latency Issues on IIS with HttpClient and TCPClient

Discover straightforward solutions to improve response times in your Blazor Server app hosted on IIS. Learn the crucial steps to resolve latency issues when using HTTPClient and TCPClient.
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Tackling Blazor Server App Latency Issues on IIS

When deploying a Blazor Server app, many developers encounter unexpected latency issues that can impact user experience. Particularly, when the app is moved from a local development environment (like Visual Studio) to IIS, it can suffer from slow initial requests—most notably with TCPClient and HTTPClient. This article dives into the causes of these delays and provides a practical solution to enhance performance.

Understanding the Problem

The Scenario

One user reported experiencing a three-second delay in their Blazor Server app on IIS, specifically during:

The TCP call during the OnInitializedAsync lifecycle method.

The first HTTPClient request upon button interaction.

In contrast, the app performed these operations instantly in the local Visual Studio environment, prompting the query: Is there any configuration adjustment needed in the app or on IIS?

The Cause

The apparent speed difference when running locally versus on IIS can often be attributed to how the app resolves addresses. In this case, the app was using localhost as the base address for client calls when deployed.

Step-by-Step Solution to Improve Latency

1. Change the Base Address

The primary step taken to resolve this issue was modifying the base address from localhost to 127.0.0.1. This is a common practice that can greatly enhance speed for local requests, and here’s why:

Resolution Time: Using localhost entails DNS resolution, which can take more time compared to the direct numeric IP address.

Direct Connection: 127.0.0.1 connects directly without the added overhead of resolving the hostname.

2. Update Your Code

To implement this fix, locate the section of your code where you instantiate your HttpClient. Replace localhost with 127.0.0.1 like so:

[[See Video to Reveal this Text or Code Snippet]]

Ensure that <port> corresponds to the port your TCP server is listening on.

3. Testing and Verification

After applying the changes:

Deploy the updated app on IIS.

Monitor the first TCP and HTTPClient calls again to confirm if the response times have improved and are consistent with local performance.

Conclusion

Latency issues when deploying a Blazor Server app on IIS can arise due to hostname resolution delays. By simply changing the base address from localhost to 127.0.0.1, you can experience faster, more reliable connection speeds for your TCP and HTTP client calls.

Don't let these minor configuration issues detract from the potential of your application. Apply these straightforward modifications and watch your application perform with the efficiency it deserves!