You can do a few things to make your app faster like:
1. Configure your database connection pool (set max connections to 20 and add timeouts)
2. Disable verbose logging in the prod eg. Fastify’s logger: true adds overhead
3. Add compression with @fastify/compress, and reduce or remove request.log.info calls in routes

The biggest wins are the connection pool config and turning off logging in production. I think this shall help you achive 20% to 30% imporvment