Optimizing the performance of an ASP.NET Core website is crucial for ensuring fast load times, scalability, and a smooth user experience. Whether you’re building a small application or a large-scale enterprise solution, these tips and best practices will help you make your ASP.NET Core website perform at its best.

1. Use Asynchronous Code (async/await)

• Why it matters: ASP.NET Core is designed with asynchronous programming in mind. When you use asynchronous code, especially when dealing with I/O-bound operations (e.g., database calls, file access, external APIs), it frees up the server to handle other requests while waiting for the operation to complete.
• How to implement: Use async and await keywords when calling methods that perform I/O-bound operations. For example, in your controllers, database access, or external API calls, prefer Task<ActionResult> over ActionResult.

2. Implement Caching

• Why it matters: Caching reduces the number of database or API calls by storing frequently requested data in memory. This results in faster response times for users and less load on your server.
• How to implement:
  • In-Memory Caching: This is useful for storing small amounts of data that are frequently accessed.
  • Distributed Caching: Use distributed caches like Redis or SQL Server Cache for larger data or when working in a multi-server environment.
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  services.AddMemoryCache();


  Example usage of caching in a controller:

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  public async Task<IActionResult> GetCachedDataAsync()
{
var cacheKey = "key1";
if (!_cache.TryGetValue(cacheKey, out string data))
{
data = await _dbContext.MyTable.ToListAsync();
_cache.Set(cacheKey, data, TimeSpan.FromMinutes(5));
}
return Ok(data);
}


3. Minimize Large Payloads

• Why it matters: Large payloads can slow down both your server and the client’s browser. Reducing the size of responses decreases load times and bandwidth usage.
• How to implement:
  • Use Response Compression Middleware to compress response sizes.
  • Return only the necessary data (e.g., limit data returned by APIs using paging or projection).
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  services.AddResponseCompression();
app.UseResponseCompression();


4. Enable HTTP/2

• Why it matters: HTTP/2 is faster than HTTP/1.1 due to features like multiplexing (allowing multiple requests to use the same connection), header compression, and server push. It significantly improves performance by reducing latency.
• How to implement: ASP.NET Core supports HTTP/2 out-of-the-box. Ensure that your server supports it (e.g., Kestrel or IIS), and no additional configuration is required.

5. Leverage Database Optimizations

• Why it matters: Inefficient database queries can slow down your application. Optimizing database access is key to improving performance.
• How to implement:
  • Use No Tracking Queries (AsNoTracking() in Entity Framework) for read-only operations to avoid unnecessary change tracking.
  • Optimize database queries using indexes, pagination, and by selecting only the required fields (projection).
  • Use Entity Framework Core wisely to avoid performance bottlenecks. For example, prefer eager loading to lazy loading when you know you’ll need related entities.
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  var products = await _dbContext.Products.AsNoTracking().ToListAsync();


6. Reduce Startup Time

• Why it matters: A slow application startup can negatively impact your user experience, especially during application restarts or cold starts.
• How to implement:
  • Precompile views to avoid view compilation on the first request.
  • Warm-up your application on startup by preloading critical services or data.

  To precompile Razor views, add the following in your project file:

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  <PropertyGroup>
<MvcRazorCompileOnPublish>true</MvcRazorCompileOnPublish>
</PropertyGroup>


7. Optimize Middleware Pipeline

• Why it matters: The order of middleware in ASP.NET Core’s request pipeline affects performance. Middleware that processes all requests should be minimal and efficient.
• How to implement:
  • Place static file middleware at the start of the pipeline to serve static assets (e.g., CSS, JS) without processing the entire pipeline.
  • Avoid unnecessary middleware and ensure that only the required middleware runs for specific routes.

  Example of ordering middleware:

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  app.UseStaticFiles();
app.UseRouting();
app.UseAuthentication();
app.UseAuthorization();


8. Use Health Checks

• Why it matters: Monitoring the health of your application is important to ensure high availability and performance. ASP.NET Core supports Health Checks to monitor the health of critical services like databases, external APIs, and memory usage.
• How to implement: Add health checks in Startup.cs and expose a health check endpoint to monitor.
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  services.AddHealthChecks()
  .AddDbContextCheck<MyDbContext>();

  app.UseEndpoints(endpoints =>
{
endpoints.MapHealthChecks("/health");
});


9. Optimize Static Files and Assets

• Why it matters: Large or unoptimized static files can slow down your website, especially on slower networks.
• How to implement:
  • Enable caching for static files by using appropriate cache control headers.
  • Minify and bundle your CSS and JavaScript files.
  • Use a Content Delivery Network (CDN) to serve static assets globally, improving load times for users in different locations.
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  app.UseStaticFiles(new StaticFileOptions
{
OnPrepareResponse = ctx =>
{
ctx.Context.Response.Headers.Append("Cache-Control", "public,max-age=600");
}
});


10. Monitor and Profile Your Application

• Why it matters: Profiling helps identify performance bottlenecks, memory leaks, and slow queries.
• How to implement:
  • Use Application Insights, MiniProfiler, or New Relic to track the performance of your application in real time.
  • Use ASP.NET Core’s built-in logging system to track issues and analyze application performance.

Conclusion

Optimizing the performance of an ASP.NET Core website involves both coding practices and infrastructure improvements. By using asynchronous programming, caching, compression, database optimizations, and health checks, you can significantly enhance the speed and scalability of your website. Ensure that you continuously monitor and profile your application to maintain peak performance as your traffic and features grow.