Just a few months ago, Microsoft detailed how Copilot Studio leverages .NET and WebAssembly (WASM) to deliver high performance directly in the browser. Now, the team has taken a major leap by migrating their WASM engine to .NET 10. This upgrade isn't just a routine version bump—it brings tangible speed boosts, simpler deployments, and reduced payload sizes. Below are the six most impactful changes that Copilot Studio users and developers should know about.
1. A Surprisingly Smooth Upgrade Path
Upgrading from .NET 8 to .NET 10 for a WebAssembly application was almost anticlimactic for the Copilot Studio team. The process boiled down to updating the TargetFramework in the .csproj files and verifying that all dependencies aligned with the new version. No messy workarounds or compatibility headaches. Within a short window, the .NET 10 build was running in production, proving that the framework’s backward compatibility is solid and that the migration effort is minimal for existing WASM projects.
2. Automatic Fingerprinting Eliminates Manual Hashing
One of the most welcome changes in .NET 10 is automatic fingerprinting of WebAssembly assets. In earlier versions, teams had to read the blazor.boot.json manifest, run a custom PowerShell script to append SHA256 hashes to file names, and then pass integrity arguments from JavaScript. All of that manual overhead is now gone. .NET 10 automatically includes a unique identifier in each published asset’s filename, providing built-in cache-busting and integrity validation without any custom code. Copilot Studio was able to delete their entire renaming script and remove the corresponding integrity logic from the client-side loader. Existing caching logic continues to work unchanged.
3. Smaller Downloads with WasmStripILAfterAOT
Performance gains also come from smaller downloads. In .NET 10, the WasmStripILAfterAOT setting is enabled by default for AOT builds. After ahead-of-time compilation, the original Intermediate Language (IL) for those methods is no longer needed at runtime, so it is stripped from the published output. In .NET 8 this option existed but defaulted to false. By removing the IL, the total download size shrinks, leading to faster page loads and lower bandwidth consumption—especially valuable for large-scale applications like Copilot Studio.
4. Dual JIT/AOT Engine Strategy Works Even Better
Copilot Studio uses an advanced packaging approach: it ships a single npm package containing both a JIT engine (for near-instant startup) and an AOT engine (for maximum steady-state performance). At runtime, both engines load in parallel—JIT handles initial interactions while AOT compiles in the background. Once AOT is ready, control seamlessly transfers over. With WasmStripILAfterAOT now active, the AOT assemblies no longer match their JIT counterparts, which initially could complicate deduplication. The team carefully manages file deduplication for bits that are identical across modes, keeping the package size efficient while reaping the startup benefits of JIT and the execution speed of AOT.
5. Simplified Deployment and Better Performance
Automatic fingerprinting not only saves development time but also improves deployment safety. Because each asset file now carries a unique fingerprint, developers no longer need to worry about stale caches or integrity mismatches. The process is fully automated, reducing human error and speeding up release cycles. Copilot Studio’s deployment pipeline now requires fewer custom steps, making it easier to push updates and roll back if needed. Together with the smaller AOT output, overall deployment size is reduced, which translates to faster download times for end users.
6. A Tip for WebWorker Users
If your application loads the .NET WASM runtime inside a WebWorker, there is a small but important configuration change in .NET 10. When initializing the runtime, set dotnetSidecar = true to ensure proper initialization in a worker context. This avoids potential timing issues and ensures that the runtime behaves identically whether running on the main thread or inside a separate worker. Copilot Studio’s team found this tip valuable during their migration and recommends it for any complex multi-threaded WASM deployment.
Conclusion
Microsoft Copilot Studio’s move to .NET 10 on WebAssembly showcases how incremental framework upgrades can deliver outsized benefits. The combination of automatic fingerprinting, smaller AOT payloads, and smooth migration saves developer hours while improving runtime performance. Whether you’re building a simple WASM app or a sophisticated multi-engine system like Copilot Studio, .NET 10 provides the tools to deploy faster and run leaner. If you haven’t upgraded yet, the path is clearer than ever.