Looks like the search index is downloaded and used locally in the browser, so this is as fast as search can get. One trade-off though is that you're limited to relatively small datasets. While this shouldn't be an issue for small-medium static sites, an index that needs to be downloaded over the wire will affect your page performance for larger sites / datasets.
In those cases, you'd want to use a dedicated search server like Algolia or its open source alternative Typesense [1]. Both of them store the index server-side and only return the relevant records that are searched for.
For eg: you'd probably not want to download 2M records over the wire to search through them locally [2]. You'd be better off storing the index server-side.
[1] https://github.com/typesense/typesense (shameless plug)