you're asking Perl to compile each of the regular expressions again every time the subroutine sasify is called. You can avoid this with the "/o" operator

This is a common misconception. In fact, the regular expressions are compiled once, at the same time as the rest of the program. The /o modifier makes a difference only when the RE includes a variable interpolation: in that case, it means the RE will contain the value of the variable at its first use, and will not change, regardless of whether the variable changes or not. In this case, since the REs are static strings, there is no re-compilation involved.