title: Database performance concerns - repeated data
body: <p>I have some database performance concerns (not yet a real issue but I  would like to make sure everything is good enough).</p>
  
  <p>I have around 10 tables that are connected. There is one main object/table that is 'mother' of all and contains the userID (these records are user specific). So, if I want to get any record from any table for specific user I would have to do lets say 5+ joins. </p>
  
  <p>I decided to avoid complications with joins so I added this userID to all tables. Now if I want to get records from a specific table for specific user I wont need any joins.</p>
  
  <p>Would this cause any issues and is it bad practice is my question.</p>
  
  <p>Microsoft technologies used for both application and database.</p>