I recently been doing some tasks for university, which include using Turbo Profiler (the software is implicitly declared in the task, sadly) for profiling C and Pascal implementations of Simpsons numerical integration. I came across very strange case, where Pascal is suspiciously much faster than C.
Pascal:
i: integer, lower: real, delta_x: real;
....
(0.0000 seconds) (30 times) x:=lower+delta_x*(2.0*i-1.0);
C:
long i, double lower, double delta_x;
....
(0.0549 seconds) (30 times) double x = lower + delta_x * (2.0 * i - 1.0);
So, what could it be, the difference between real and double (and integer and long) or just Pascal's compiler better at processing math operations?
Don't believe those numbers. If you want to measure time, put a loop of 10^6 or 10^9 iterations around the top subroutine, and count seconds. If you want to see what fraction of time goes into that statement, use stack-sampling.