I wish OsmAnd all the best, but ever since the app was created, its map rendering performance has been stuck in the 2010s, no matter how much faster our devices have gotten since then.
There is justification for it for sure (see https://github.com/osmandapp/OsmAnd/issues?q=is%3Aissue+slow... for a few), and I love OSM out of principle, but as a product, it will remain my last resort until the user experience is tolerable.