How many pages can bubble apps handle?

There are no “static” Bubble pages - at least not native Bubble pages. With a paid plan, you can upload files to your site root and create a static page that way, but that’s the only way AFAIK (and of course, you’d be missing the whole point of Bubble with that approach).

It seems to me your app’s SEO would benefit much more from your URL structure and page content - perhaps using a purpose-built plug-in.

And with Bubble’s recent Cloudflare integration, speed shouldn’t be much of a concern.