Blazor Performance Optimization: Lazy Loading Guide

Blazor is a powerful framework for building interactive web applications using .NET. As applications grow in size and complexity, performance optimization becomes crucial. One effective technique to enhance performance is lazy loading. In this blog post, we will explore lazy loading in Blazor and understand how it can improve the loading speed and responsiveness of your applications.

What is Lazy Loading? 

Lazy loading is a technique that defers the loading of certain resources or components until they are actually needed. Instead of loading everything upfront, lazy loading allows you to load specific parts of your application on-demand, reducing the initial load time and improving overall performance.

Benefits of Lazy Loading in Blazor

  1. Faster Initial Load: By loading only the essential components and resources during the initial page load, lazy loading minimizes the amount of data transferred, resulting in faster load times.
  2. Reduced Bandwidth Usage: Lazy loading helps conserve bandwidth by fetching additional components or data only when they are required. This is particularly beneficial for mobile users or those on slower network connections.
  3. Improved User Experience: With lazy loading, users can start interacting with the application sooner, as they don’t have to wait for the entire application to load. This improves the perceived performance and provides a more responsive user experience.

Implementing Lazy Loading in Blazor

To implement lazy loading in Blazor, we can leverage the dynamic component loading feature introduced in Blazor .NET 6.

  1. Identify the Components to Lazy Load: Analyze your application and identify components that are not immediately necessary on the initial page load. Examples may include complex data grids, charts, or sections of the application that are accessed less frequently.
  2. Create Placeholder Components: For the components that will be lazily loaded, create lightweight placeholder components that are initially rendered in their place. These placeholders can be simple loading spinners or placeholders with minimal content.
  3. Load Components On-Demand: When the user triggers an action or navigates to a section requiring a lazily loaded component, dynamically load the actual component and replace the placeholder. This can be done using mechanisms like RenderFragment or by utilizing third-party libraries such as Blazor.Lazy.
  4. Manage State and Data Dependencies: Consider any state or data dependencies of the lazily loaded components. Ensure that the necessary data is available and propagated to the components when they are loaded.
  5. Graceful Error Handling: Handle any errors that may occur during the lazy loading process, such as network failures or component loading failures. Provide informative error messages or fallback options to prevent a poor user experience.

Sample Lazy loading

Here are a few code snippets to illustrate the implementation of lazy loading in Blazor

1. Placeholder Component 

lazy loading in Blazor example 1

2. Lazily Loaded Component

lazy loading in Blazor example 2

3. Lazy Loading in Parent Component: 

lazy loading in Blazor example 3

In the example above, the PlaceholderComponent serves as a lightweight component initially rendered in place of the LazilyLoadedComponent. The LazyComponent from the Blazor.Lazy library is used to encapsulate the lazy loading functionality. When the LoadLazilyLoadedComponent method is invoked, it simulates an asynchronous loading delay and then replaces the placeholder with the actual LazilyLoadedComponent.

Remember to include the necessary using statements and reference any required libraries in your Blazor project to utilize lazy loading functionality.

These code snippets provide a basic implementation of lazy loading in Blazor. You can further enhance and customize the implementation based on your specific requirements and application structure.

The code snippet provided uses the Blazor.Lazy library as an example. Make sure to install the library via NuGet or use an alternative lazy loading solution if desired 


Lazy loading is a powerful technique in Blazor to optimize performance by deferring the loading of non-critical components and resources until they are needed. By reducing the initial load time and conserving bandwidth, lazy loading can significantly enhance the user experience of your Blazor applications. Remember to identify the right components to lazy load, create placeholders, and load components on-demand while considering state management and error handling.

By adopting lazy loading techniques in your Blazor applications, you can deliver fast, responsive, and highly performant web experiences. So, why wait? Start leveraging lazy loading in Blazor today and take your application performance to the next level!

Additionally, if you want to explore more about the topic, you can check out the informative blog post titled “Creating Static Images in Blazor: A Complete Guide” for further insights and guidance.


Tips for writing clean code in C#

This post will help you speed up your C# code and provide many tricks that every professional developer must know.

1. Validating input “first”

Look at the code snippet below

Validating input “first”

In this method we have many lines of code and we need to read all the code to find the last line that throws an exception if the argument is null. Instead, we can validate the input first. This tells the viewer of the code how a given method should be used.

The below code is rewritten with the reverse order of if and else statements.

reverse order of if and else statements

You can now quickly tell what is the valid argument for this method

2. “Else” is not always required

Let’s continue with the same previous example. If an employee is null we throw an exception and code does not continue to execute. So there is no need for an else block. Having an else block here only increases the indentation of the code. Here is a better way to write this code.

“Else” is not always required

3. Auto-property Initializers

One of the features added from C# 6 onward is a way to initialize properties directly like fields. We usually create constructors to initial properties like below.

Auto-property Initializers

Instead of the constructor used above we can directly initialize the property as shown below.

directly initialize the property

4. Null-conditional Operator

Many times we would have encountered the following type of coding for checking an object for null before accessing one of its members.

Null-conditional Operator

From C# 6 onwards we have a null-conditional operator (?) that evaluates null. If the object is null then the value null will be returned.

 value null

In the above example there are two null-conditional operators, one checks null in the employee object and another checks null in the address object present inside the employee. If any one is null then addressID will be set to null.

5. Null-coallescing operator

Continuing from above example, in case we do not want null value to be returned and want addressId to be an integer with default value ‘0’ when employee or address is null. We can use the null-coallescing operator (??) as shown below.

Null-coallescing operator

6. Expression Bodied Members

We can often encounter methods having single line return statement like below

Expression Bodied Members

Instead of above we can rewrite using expression bodied members, thus it reduces line indentation.

expression bodied members