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Discussion on: Should Frontend Devs Care About Performance??

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peerreynders • Edited on

Just some side points.

Once the code has been downloaded, the amount of code makes no difference to performance.

That rationale makes sense from an SPA perspective.

But Marko, Astro and Qwik are pursuing partial or progressive hydration to enable next-generation MPA‡; if you can load SSR HTML and go interactive much quicker than an SPA there is no need for client-side routing. So keeping the "critical JavaScript" to an absolute minimum, lazy loading the rest (which may never be needed) is what next-gen MPAs are based on.

‡ at this point Remix is focusing on progressive enhancement. For the time being they are not convinced about the benefits of islands/partial hydration. But ultimately that may simply be a limitation of the React mental model as each island would have to be a separate component tree (and any inter-island communication would have to happen outside of React).

then your target audience probably can't effectively run ANY React / Angular / jQuery / whatever app.

Actually in 2019 Rich Harris mentions that Svelte was used for the Brazilian Stone Point-of-Sale device because React, Vue etc. simply imposed too much overhead on the hardware. This is just one example of what is often identified as a "resource-constrained device".

Similarly in the mobile space there are cases where the CPU cores are getting smaller ("more power efficient"; though more numerous) which means single thread performance is decreasing (and today's predominant web technologies rely on single thread performance) - this leads to a situation where a $400 iPhone SE has better "web performance" than a $1400 Samsung Galaxy S20 Ultra—because the iPhone has two (of six) cores that are more performant than any one of Samsung's 8 cores.

Finally performance improvements over time for mobile devices is strongly coupled to the device class.
single core scores

The graphic shows that budget devices aren't really improving that much—their feature is that they are inexpensive, not performant. Some projections stipulate that most of the future growth in the mobile market will be at the lower end, creating a situation where performance of the "median device" could be going down.

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