Best practices can slow your application down
Use best practices but carefully.
This is the title from stackoverflow blog post.
Yes you hear that right. When building applications we encapsulate lot of common uses functions into services or common use classes. And some times those queries are not efficient but as we enforce reusability, the same is query is used at multiple places. And because of reusability we might avoid writing joins or better queries and that may leads to performances issues to the applications.