.NET 10: Zip and GZip API Improvements

Introduction

Compression APIs like ZipArchive and GZipStream have been part of .NET for years. They’ve reliably powered file packaging, log compression, backups, streaming, and more.

With .NET 10, these APIs don’t change in surface, but under the hood they get meaningful enhancements:

• Better performance on large archives
• Smarter asynchronous behavior
• More efficient processing of concatenated GZip streams

Today we’ll explore what’s improved, what remains the same, and how to use these APIs effectively with real code examples.

Why These Improvements Matter

Compression is core to many workflows:

• Distributing build artifacts
• Backing up data
• Streaming logs or metrics over the network
• Serving compressed assets to clients

Earlier versions of .NET handled these use cases, but there were inefficiencies:

• Synchronous wrappers over async I/O
• Suboptimal buffering strategies
• Limited support for concatenated GZip members

.NET 10 addresses these pain points with internal optimizations that improve throughput and resource usage.

What Hasn’t Changed

An important design goal was no breaking API changes:

• Method signatures are the same
• Existing code compiles as before
• No migration effort required

.NET 10 delivers better performance without rewriting your code.

Major Enhancements in .NET 10

Here’s a high-level summary of what’s new under the hood:

These changes mostly live inside the runtime and framework libraries. You benefit immediately simply by targeting .NET 10.

Example 1 – Extracting a Zip Archive

The code below is the same you’ve written before, but on .NET 10 it runs noticeably faster for large or numerous entries:

What Has Improved

• Better async I/O performance
• Reduced internal locking
• Efficient target buffering

These runtime optimizations make extraction especially faster when:

• The archive contains many small files
• Extraction happens over slow storage
• Cancellation tokens are used

Example 2 – GZipStream and Concatenated Files

GZip files aren’t always a single compressed blob. Many tools produce concatenated GZip files: multiple gzip members appended one after the other.

The visual from earlier in this post shows how these look internally — multiple compressed blocks as one logical file.

Here’s the code that reads such a file:

What’s Better in .NET 10

• Smarter detection of GZip member boundaries
• Lower overhead when reading multiple blocks
• Better async read performance

This means your decompression logic is simpler and faster, even with log-style, multi-member GZip files.

Visualizing Concatenated GZip Internals

Each concatenated gzip file consists of independent gzip members:

Unlike older implementations that treated everything as a single stream, .NET 10 handles each block more efficiently at the library level. You will notice the enhancement most when:

• Extracting very large ZIP archives
• Working with huge GZip streams
• Processing GZip logs with many concatenated members
• Streaming compression over network or file I/O

Even if you haven’t changed your code, your application gets faster and more efficient by targeting .NET 10.

Conclusion

.NET 10 brings meaningful and practical improvements to core compression APIs:

• No breaking changes
• Better performance out of the box
• Improved gzip block handling
• Smoother async behavior

Whether you’re working with ZIP files, large gzip logs, or asynchronous pipelines, these enhancements make your existing code better — without rewriting a thing.

Happy coding!