I think you are trying to say that references are not aliased but copied in "aliasing situations" to avoid some overhead...

But if you look at the following results you will notice that the ref of an alias is still identical while the ref of a copy isn't. (I used @R to keep the refcount up and hence avoid the reuse of freed addresses)

  DB<55> @R= map { \$_ } $a

  DB<56> x @R
0  REF(0x31fae58)          # 
   -> ARRAY(0x3353230)
           empty array
  DB<57> x \$a
0  REF(0x31fae58)          # same
   -> ARRAY(0x3353230)
           empty array
  DB<58> $b=$a

  DB<59> x \$b 
0  REF(0x3353a58)          # different
   -> ARRAY(0x3353230)
           empty array
  DB<60>
[download]

  DB<64> p \$a == $R[0]
1
  DB<65> p \$a == \$b

  DB<66>
[download]