I'm planning to build an application which will end up displaying duplicate content.
app.domain.com/content/ID # Completely rendered on the client, behind a wall of JS
www.domain.com/content/ID # Server-rendered, SEO-friendly
Under app.domain.com
I'll be serving a React SPA that renders completely on the client.
Under www.domain.com
I'll be serving the same React application but rendered on the server, to improve SEO.
The content on both applications will be the same, but presumably the server-rendered version will have better SEO. To avoid duplicate content problems, I'll be following Google's "Consolidate duplicate URLs" guide. I will:
- Specify a preferred domain:
www.domain.com
. - Set a
rel=canonical
header in my response for pages underapp.domain.com/content/ID
pointing to the correspondingwww.domain.com/content/ID
URL.
Here is my question: which application's page speed counts towards SEO? Is it the page speed of the client-side rendered application (slow because of all the JS that needs to be downloaded in a blocking way) or is it the page speed of the server-render, SEO-friendly version?
app.domain.com
version because it will render the same content but inside of an application that allows the user to interact with it more heavily.