I guess you can look at it this way, your task is simular to making a round object that will roll down a hill, C lets you make just a simple wheel with no other baggage, Perl lets you make a wheel but gives you all the baggage that comes along with making the rest of a car. There is overhead to all of the memory managment, hash tables, etc that comes with even a one liner perl script -- stright C code can avoid most of this if it is not needed. On the other hand your C app as it grows into the "car" where it becomes more complecated will start to perform much more like the perl script overall.
Of course. Perl is a C application and is only slower and bigger because it must be so flexible. As a C application becomes more flexible there's a point at which it starts working its way into perl's territory.