Blazor has the ability to enable interactivity using SignalR while initializing the WebAssembly runtime in the background. After WebAssembly assets get downloaded, future visits to the site will use WebAssembly for interactivity, since they will load quickly from the cache.

However, in addition to downloading WebAssembly resources, the dotnet.create() JS API also performs other initialization that blocks the main thread (for about ~85 ms on my machine). This can contribute to the webpage feeling sluggish.

If we had an API like dotnet.download() that only downloaded WebAssembly resources and skipped other initialization, that could help the case where Blazor's "Auto" render mode uses Server interactivity.