Great episode — the explanation of nested islands is excellent and very easy to follow. I rebuilt the example locally and tested all scenarios.

I ran into a small behavior that I’m not sure I fully understand yet:

I have a metrics area that is lazy-loaded with a short delay (about 2 seconds).

Lazy loading works as expected

The placeholder is shown correctly

Manual refresh inside a nested island works perfectly

However, when I change a global filter (for example a period selector), the parent island re-renders and — because of always: true — the nested metric islands re-render as well.

At that point, the entire page (not just the metric islands) appears to “hang” for those ~2 seconds until all metrics are loaded again.

From a UX perspective, I expected this to behave more like a full page reload:

the page updates immediately

placeholders are shown again

metrics load progressively in the background

So I’m wondering:

Is this behavior expected when combining always: true with lazy-loaded nested islands?

Did I miss a recommended pattern to avoid blocking the UI during that delay?

Or is the idea that global filter changes should generally not rely on delayed/lazy islands?

Everything else behaves exactly as shown in the video — it’s just this interaction that surprised me a bit.

Nested Islands