Using Self as a Method Default

Here's something that's weird.

The fastest method gets 57 fps (in a 1 million cycle loop with Flip 0).

If I do it this way (notice the 'this' field):

Type TVector3
     Field x:Double, y:Double, z:Double
     Field this:TVector3

     Function Create:TVector3(x:Double = 0, y:Double = 0, z:Double = 0)
          Local v:TVector3 = New TVector3
          v.this = v
          v.x = x
          v.y = y
          v.z = z
          Return v
     End Function

     Method Add(a:TVector3, b:TVector3 = Null)
          If b = Null Then b = self.this
          self.x = b.x + a.x
          self.y = b.y + a.y
          self.z = b.z + a.z
     End Method
End Type

I get 56 fps which isn't a bad hit at all and lets me write it both ways of v1.add( v2 ) and v1.add( v2, v3). For some reason, setting b to a field that's holding the type is faster than just setting b to self. /shrug