This is unfortunately the tell-tale sign of a memory leakage. This command
ps --sort -rss -eo rss,pid,command | head
will tell you who the culprit is. Solving a problem like this is way above my pay grade, since it can basically be done only by the program/system developers. You may try to contact them to report the problem.
Edit:
Don't you have the curl command wrong? Should it not be
sudo curl -L http://cpanmin.us | perl - --sudo App::cpanminus
instead?