Quick answer
How do you enjoy Porto slowly?
The best way to enjoy Porto slowly is to choose fewer places, walk between them with time, pause in gardens and cafés, follow the Douro, notice tiles and old façades, and avoid turning the city into a race.
For a slower Porto experience, combine the historic centre with places like Palácio de Cristal, Serralves, Parque da Cidade, Foz, Gaia coastal trails and quieter neighbourhood streets.