Blazor WASM performance has improved dramatically across .NET versions. Here are the most impactful optimization techniques.

Reduce Initial Download Size

• Enable IL trimming: <PublishTrimmed>true</PublishTrimmed>
• Enable AOT compilation for CPU-intensive apps
• Use lazy loading to defer large assemblies
• Minimize third-party NuGet packages

Minimize Re-renders

• Override ShouldRender() to skip unnecessary renders
• Use @key in foreach loops
• Avoid inline lambdas as parameters in tight loops

Virtualize Large Lists

Use the <Virtualize> component for any list with more than ~50 items.

Thread Safety for Background Updates

When triggering UI updates from background threads (timers, SignalR), always use:

await InvokeAsync(StateHasChanged);

Pre-rendering (Blazor 8+)

The server renders initial HTML before the WASM runtime loads, dramatically improving perceived load time on first visit.

Reference:

Wikipedia: Web Performance

https://en.wikipedia.org/wiki/Web_performance