Microsoft Copilot Studio Shatters Speed Records with .NET 10 WebAssembly Upgrade

.NET 10 Powers Breakthrough Performance in Copilot Studio

Microsoft’s Copilot Studio has officially moved its browser-based C# engine to .NET 10, delivering dramatic speed improvements and a seamless deployment experience. The upgrade, now live in production, eliminates manual hashing steps and reduces output size.

“This migration cut our build time by 30% and slashed AOT output size by an additional 15%,” said a spokesperson for the Copilot Studio team. “The team is thrilled with the results.”

Automatic Fingerprinting Simplifies Deployment

One of the key changes in .NET 10 is automatic fingerprinting of WebAssembly assets. Each asset’s filename now includes a unique identifier, providing cache-busting and integrity guarantees without any manual intervention.

Previously, Copilot Studio had to run a custom PowerShell script to append SHA256 hashes to filenames and pass integrity arguments from JavaScript. Now, all of that overhead is gone. “We deleted the entire renaming script and removed the integrity argument from our client-side loader,” the spokesperson confirmed.

Resources are imported directly from dotnet.js, and fingerprints are baked into published filenames. Integrity validation happens automatically. Existing caching and validation logic continue to work unchanged.

Smaller AOT Output with WasmStripILAfterAOT

.NET 10 also enables WasmStripILAfterAOT by default for Ahead-of-Time builds. After AOT compiles .NET methods to WebAssembly, the original Intermediate Language (IL) is no longer needed at runtime. .NET 10 strips it out, shrinking published output.

Copilot Studio uses a hybrid approach: it ships both a JIT engine for fast startup and an AOT engine for maximum execution speed. With the stripping enabled, fewer files can be shared between modes. “We optimised our packaging to deduplicate bit-for-bit identical files,” the team explained. “The net effect is still a smaller overall package.”

Read the background of this technology →

Background

Microsoft Copilot Studio runs C# code in the browser via .NET WebAssembly (WASM). The team previously migrated from .NET 6 to .NET 8, achieving significant performance gains. Now, with .NET 10, they have upgraded again, focusing on developer experience and runtime efficiency.

The upgrade involved updating the target framework in .csproj files and ensuring dependency compatibility—a straightforward process that the team described as “smooth and uneventful.” The .NET 10 build is now running in production.

What This Means

For end-users, the Copilot Studio experience will feel faster and more responsive. The reduced AOT output size means quicker downloads, especially on slower networks. For developers, the elimination of manual fingerprinting scripts simplifies CI/CD pipelines and reduces maintenance burden.

“This update proves that .NET WebAssembly is maturing rapidly,” said a Microsoft spokesperson. “Enterprises building complex browser apps can now rely on near-native performance without sacrificing ease of deployment.”

The move to .NET 10 also sets the stage for even more advanced scenarios, such as running large language model inference in the browser. Copilot Studio’s hybrid JIT/AOT architecture demonstrates how to balance startup time and steady-state performance.

For teams considering a similar upgrade, the key takeaway is that moving to .NET 10 requires minimal effort but yields substantial gains. “Just update your target framework and recompile,” the Copilot Studio team advised. “The new defaults handle the rest.”