https://devblogs.microsoft.com/dotnet/check-out-csharp-12-preview/
ASP.NET Core updates in .NET 8 Preview 3
Announcing .NET 8 Preview 3

Ну и как же без Get started with OpenAI in .NET

How can I access OpenAI models
Access to models like GPT is available via REST APIs and libraries.

Additionally, Azure OpenAI Service provides Azure customers with access to OpenAI’s advanced language AI models such as OpenAI GPT-4 with the security and enterprise promise of Microsoft Azure.

The APIs are co-developed with OpenAI to ensure compatibility and a smooth transition between the two. Customers also benefit from private networking, regional availability, and responsible AI content filtering.

https://devblogs.microsoft.com/dotnet/check-out-csharp-12-preview/
ASP.NET Core updates in .NET 8 Preview 3
Announcing .NET 8 Preview 3

Announcing .NET 8 Preview 5

Некоторая часть

Optimized ThreadStatic field access for GC-type
Field accesses that are marked as ThreadStaticLocal are now optimized for primitive types. With PR#85619, we have optimized reference type field access as well. These changes have led some really good improvements in a number of benchmarks: (133 on windows/arm64, 23 on windows/x64, 16, 13, 11 improvements).

Arm64
Preview 5 also brings a number of few peephole optimizations:

With PR#85032, we enabled peephole optimization to replace str pair with stp.
With PR#85657, we enabled peephole optimization of replacing pair of ldr/str with ldp/stp inside prolog.
General optimizations
Our team has released a number of general optimizations that include:

x64 instructions such as movzx, movsx and movsxd have been optimized in PR#85780, which slightly improved code-gen by eliminating more redundant mov instructions.
PR#86318 improved constant folding for some frozen objects (non-GC objects). It reduced the size of the generated code by almost 10 times (e.g., 424 bytes to 41 byte).
AVX-512
PR#85389 enabled AVX-512 for block unrollings, which increases ranges where it previously used to fallback to memcpy/memset and reduced the execution time by half.
Various integer intrinsics are enabled for AVX512F, AVX512BW and AVX512CD, PR#85833.

Announcing .NET MAUI in .NET 8 Preview 5
ASP.NET Core updates in .NET 8 Preview 5