TC relationship with IR in constrained portfolio

Can someone explain the relationship between TC relationship with IR in constrained portfolio?

From what I’ve learnt in the textbook and searched online, I’ve known that

  • In a constrained portfolio, IR decreases with the “aggressiveness of the strategy”
  • In a constrained portfolio, TC < 1
  • active risk increases but active return does not increase so IR decrease

I’m confused about all these statements, what is the meaning of aggressiveness in this context? and why does it limit TC? how come TC decreases but active risk increase and active return does not increase???