V11 Preview 3 Update: HTTP/3 early request processing improvement added to Kestrel Overview

[wadepickett]

Description

PR #36991 introduces the following new feature for ASP.NET Core in .NET 11 Preview 3:
HTTP/3 starts processing requests earlier — Kestrel no longer waits for the control stream and SETTINGS frame before processing HTTP/3 requests, reducing first-request latency.

This Kestrel overview page is the landing page for Kestrel documentation. While no specific line changes are critical, adding a note about the HTTP/3 early request processing improvement under the features list would help developers discover the performance improvement. This is a lower priority since the detail belongs in the HTTP/3 sub-article.

Suggested changes

1. Add a new section after "HTTP/3 benefits" (after line 48, before "HTTP/3 requirements")

## Early request processing

:::moniker range=">= aspnetcore-11.0"

Starting with .NET 11, Kestrel starts processing HTTP/3 requests without waiting for the control stream and SETTINGS frame first. This optimization reduces first-request latency on new HTTP/3 connections.

In previous versions, Kestrel waited to receive the QUIC control stream and its initial SETTINGS frame before processing any request streams. This is no longer required, which means the first request on a new connection completes faster.

:::moniker-end

2. Expand the HTTP/3 bullet in the features list (around line 27)

  * HTTP/1.1, [HTTP/2](xref:fundamentals/servers/kestrel/http2) and [HTTP/3](xref:fundamentals/servers/kestrel/http3) (with early request processing for reduced latency in .NET 11+)

Page URL

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/servers/kestrel?view=aspnetcore-10.0

Content source URL

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/fundamentals/servers/kestrel.md

Document ID

3e0e12c2-e544-5655-e001-d2ec180b11a8

Platform Id

1464e7f0-899a-541e-4b11-134d7f16a7be

Article author

@tdykstra

Metadata

• ID: f22dcddb-0c25-be1a-9a02-9e71dce86bdb
• PlatformId: 1464e7f0-899a-541e-4b11-134d7f16a7be
• Service: aspnet-core
• Sub-service: fundamentals

Related Issues

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Associated WorkItem - 569849

[wadepickett]

Additonal information for GitHub Copilot:
Also look through the related PR #36996 for hints on how to word the new content in case that is helpful.