Will replacing Webflow's built-in search hurt my SEO or slow my site down?

No. Typesense runs as a separate search service that your pages only call when a visitor actually searches. Your Webflow pages, hosting, and the way Google crawls your content all stay exactly as they are. The search index is an addition that sits alongside your site, not a replacement for it — so there's no SEO penalty and no page-load slowdown.