There may be more opportunities for reducing the size of the solr index. The size of the index is nondeterministic and fluctuates +/- 150MB each time we generate it. Adding an optimization step after generating should be able to bring the size down, and there are other tweaks we can do to the data captured in the index that could reduce the size without compromising search quality. Here are some resources:

https://dzone.com/articles/solr-index-size-analysis
https://stackoverflow.com/questions/10080881/solr-index-size-reduction

I tried the basic optimization curl http://localhost:8983/solr/portal/update?optimize=true command but it didn't have any effect; maybe the optimization is already in place (though I couldn't find anywhere it was being triggered).

Jared suggested sending a commit request after the optimize request:

        // send GET request to solr to commit the changes
        self.client
            .get("http://localhost:8983/solr/portal/update?commit=true")
            .send()
            .await
            .unwrap();