WASM file size optimization

[kellytk]

I'm submitting a ...

• feature request

WebAssembly is the future of web-based code distribution but its files are large. The large file size imposes an unfavorable cost to first-x performance metrics such as first contentful paint.

How could that problem be optimally solved and which pieces of the Yew+wasm-bindgen+wasm-pack+bundler stack would it involve?

Possible Solution

Introduce a method of annotating component trees with something like a load priority. Each load priority scope would become a separate WASM file. When the app is loaded, its WASM files would be loaded based on their load priority. load priority would need to be overridable by user demand. For example, if a dropdown menu is marked low priority and it hasn't loaded by the time a user clicks the menu's button to present it, it would be immediately fetched, mounted, then presented.

[Boscop]

Someone recommended wasm-opt to me.
With opt-level = "z" you degrade performance to get a small size.

[kellytk]

Regarding the possible solution I suggest above, a lazy load priority would probably be helpful for features that should not be loaded until used.

[kellpossible]

just out of interest, what is the smallest binary size someone has managed to achieve with Yew (even a simple hello world)?

[jstarry]

@kellpossible not yet! I'd love to start tracking that!

[evbo]

@kellytk I read the above linked roadmap but am not seeing "lazy load" as a feature. How did this get implemented now, is there a way to lazy parts of a Yew application for faster startup?