Both of these features are poorly documented.

In the book, it says that the nightly feature enables the function call syntax for signals, but is there something more to it?
In the code for js-framework-benchmark there is comment that says that for benchmarking both the delegation and nightly features will be enabled. So do they have performance benefits?

Enabling the nightly feature seems increase the wasm size by a few KB.

And the delegation feature isn't even mentioned in the book.

It would be nice if more information was available about this.
Thanks!