Blazor WASM Tasks

I have just seen that Blazor WASM does not currently support multiple threads. So if you do a Task.Run() it will actually run on the main thread and block the UI.

So if I wanted a Blazor WASM application that did some expensive processing. For example

a) A computationally expensive numerical computation

await Task.Run(() => SlowComputation())

or

b) Performing a slow query in a SQLite DB

would I essentially just have to accept that the UI will be blocked?

I'm currently in the process of converting a winforms app to Blazor wasm and we use Task.Run() quite frequently.