Aura:if (Aura if) evaluates the istrue expression on the server and instantiates components in either its Body or Else attribute. Only one branch is created and rendered. Switching current state unrenders and destroys the current branch and generates the other. You can create as many states as you need.
One of the main benefit about aura:if is the reduction of the volume of elements that need to get created at any given time, therefore increasing speed and performance.