Copilot Studio Accelerates Performance with .NET 10 and WebAssembly Upgrade
Microsoft’s Copilot Studio has taken a significant leap forward by migrating its .NET WebAssembly (WASM) engine to the latest .NET 10 release. This upgrade brings substantial performance improvements and simplifies deployment processes, building on earlier gains from the move from .NET 6 to .NET 8. In this article, we explore how the transition unfolded and the key enhancements that make .NET 10 a game-changer for browser-based applications.
A Seamless Upgrade Experience
Upgrading an existing .NET 8 WASM application to .NET 10 proved to be remarkably straightforward for the Copilot Studio team. The primary steps involved updating the target framework version in the project’s .csproj files and verifying compatibility of all dependencies with the new runtime. Once those adjustments were made, the .NET 10 build was ready for production deployment without major hurdles. This ease of migration highlights the backward compatibility and thoughtful design of the .NET ecosystem.
Automatic Fingerprinting Streamlines Deployment
One of the most impactful improvements in .NET 10 for WebAssembly applications is automatic fingerprinting of WASM assets. When an application is published, each asset’s filename now includes a unique identifier derived from its content. This built-in feature provides both cache-busting and integrity verification without any manual scripting or additional configuration.
Previously, Copilot Studio—like many WASM-based applications—had to implement a custom process to achieve the same result:
- Parse the blazor.boot.json manifest to list all published assets.
- Run a PowerShell script that appended a SHA256 hash to each filename.
- Pass explicit integrity arguments from JavaScript when requesting each resource from the server.
With .NET 10, all these manual steps are eliminated. Resources are now imported directly from dotnet.js, fingerprints are part of the filenames generated during publishing, and integrity validation occurs automatically. The Copilot Studio team was able to delete the custom renaming script and remove the integrity argument from the client-side resource loader. Existing caching and validation logic on top of these resources continues to function without modification.
Tip: If you load the .NET WASM runtime inside a WebWorker, set
dotnetSidecar = trueduring initialization to ensure proper behavior in a worker context.
Smaller AOT Output with WasmStripILAfterAOT
Another headline feature in .NET 10 for WebAssembly is that WasmStripILAfterAOT is now enabled by default for AOT (Ahead-of-Time) builds. After .NET methods are compiled to WebAssembly, the original Intermediate Language (IL) for those methods is no longer needed at runtime. .NET 10 strips this IL from the published output, reducing the overall payload size. In .NET 8, this feature existed but defaulted to false.
Copilot Studio uses a sophisticated packaging strategy to balance startup time and steady-state performance. It ships a single NPM package containing both a JIT engine (for fast startup) and an AOT engine (for maximum execution speed). At runtime, both engines are loaded in parallel: the JIT engine handles initial user interactions, then hands control over to the AOT engine once it is fully ready. Files that are identical between the two modes are deduplicated to keep the package size minimal.
Because WasmStripILAfterAOT produces AOT assemblies that no longer match their JIT counterparts, fewer files can be deduplicated. However, the overall savings in download size from stripping IL outweigh the loss of deduplication, leading to net performance gains. The Copilot Studio team reported noticeable reductions in payload weight, which directly translates to faster load times for end users.
Additional Performance and Developer Experience Benefits
Beyond fingerprinting and AOT size reduction, .NET 10 introduces several other optimizations for WebAssembly applications. These include improved garbage collection, better interop with JavaScript, and faster module instantiation. Developers also benefit from enhanced debugging capabilities and more consistent tooling across platforms.
The Copilot Studio team found that the upgrade not only simplified their deployment pipeline but also improved runtime performance metrics. Early benchmarks show that .NET 10 delivers faster execution times for complex C# logic running in the browser, further closing the gap between native and web performance.
Looking Ahead: The Future of .NET in the Browser
The success of Copilot Studio’s migration to .NET 10 underscores the growing maturity of .NET WebAssembly technology. As .NET continues to evolve, we can expect even tighter integration with modern web standards and more seamless developer experiences. The automatic fingerprinting and default IL stripping are just the beginning—future releases may bring further innovations in packaging, debugging, and performance tuning.
For teams considering a move to .NET 10, the Copilot Studio case study demonstrates that the upgrade path is smooth and the benefits are tangible. Whether you are building a complex enterprise application or a lightweight interactive component, .NET on WebAssembly offers a compelling way to bring C# and .NET’s power directly to the browser.