Normalization can adversely affect performance. As the number of models increase, the number of joins needed to answer a query also increase. For instance, to find the number of superheroes with the Freeze capability in the USA, you will need to join four tables. Prior to normalization, any information can be found by querying a single table.
You should design your models to keep the data normalized. This will maintain data integrity. However, if your site faces scalability issues, then you can selectively derive data from those models to create denormalized data.
Best Practice:
Normalize while designing, but denormalize while optimizing.
For instance, if counting the sightings in a certain country is very ...
