Since there is a subroutine call there is some overhead in making the change. However, the subroutine itself only changes some bits in $^H, so it's not a difficult call. If you can wrap the no strict 'refs' around a larger lexical scope you may benefit (such as around a loop). Perhaps you can make sure you don't use anything but hard refs except for that part, and keep
the script. It'll probably be strict happy, but there is some risk involved. I wouldn't worry much though.