As others have pointed out, the best thing to do is leave the system's perl as it is and install your own. We recently had some discussion on that (How should I manage CPAN when using two versions of Perl in my computer?). It is very easy to do and very convenient, just compile and install any version of perl you need in "/usr/local/perls/perl-X.X.X" (see this post in Stack Overflow for reference), and then make symbolic links of the executables to "/usr/local/bin".

If your problems arise from using different and possibly old versions of gcc, try using the utility "update-alternatives", which I find very useful (see this link).

Good luck!