I ran pretty much the same program in C and in Perl, and the C program ran about 200 times faster.
In a simalar vein, I ran the Pontifex encryption algorithm (Solitare) on a fairly slow computer with both the C and Perl versions on the American Standard Bible. The C version ran in a minute and a half. I just killed the Perl version after an HOUR and a half.
Considering purely speed with most kinds of mathmatical algorithms leads you to think C is better to Perl. However, modern computing power almost makes this problem a non-issue for anything but 3D games or high end simulators. If getting things done in Perl is easier for you (which, of course, it is :-) ), I think Perl will save more time.