I currently have a database with two tables called Articles and Tags . In order to allow articles to be in multiple categories i have a many to many relationship. Is it a mistake to have such a design in terms of performance? or should i remove the relationship between these two table and add a third table as a bridge (articlesTags)?
There's nothing inherently wrong with having a many-to-many relationship, you'll just need to create a Junction Table (which is what it sounds like you're referring to with articlesTags) to facilitate that relationship.