Investigate Blazor WebAssembly startup performance characteristics (original) (raw)

Even when Blazor WebAssembly assets are cached, the time it takes for a Blazor WebAssembly app to initialize can be significant. We should investigate ways to further optimize Blazor WebAssembly initialization to reduce this startup time.

Some preliminary investigation suggests that Blazor-specific startup (everything that happens after the code in Program.cs starts executing) accounts for at least half the total initialization time.

We should:

• Add instrumentation to measure how long various initialization stages take
  • Such stages include loading cached assets, initializing the .NET WebAssembly runtime, and many of the steps between the start of the app's entrypoint and the first interactive render
• Collect traces for Blazor-specific initialization code
• Given those results, determine what work can be done to minimize WebAssembly startup time
• Consider benchmarking daily builds so we can track these detailed performance measurements over time

Related issues:

• Improve the load time performance of Blazor WebAssembly apps on low-end mobile devices #42284
• [Blazor] Auto Render not working properly in .NET 8 and page locks until WebAssembly start #52154