I calculated the 20,000th number on my computer, and it took 9 seconds. Is my program slow, or just my computer?

Code:

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
/* number of max three digits (max digits = MAX3DIGITS*3) */
#define MAX3DIGITS 100000
/* struct that holds three digits (like 503) */
struct three {
unsigned n : 10;
};
/* a whole number made up of struct threes */
struct num {
struct three n[MAX3DIGITS];
} number[2];
int main() {
int x, y, n = 0; /* temp/loop vars and # of calculations (loop count) */
int naim, prev = 0; /* the aim number and which number is current */
int digits = 2; /* digits taken (in threes) */
fprintf(stderr, "\nEnter the fibonacci number to compute:\n");
scanf("%i", &naim);
number[0].n[0].n = 0;
number[1].n[0].n = 1;
while(!kbhit() && ++n < naim && digits <= MAX3DIGITS) {
//fprintf(stderr, "\r%i", n);
prev = !prev;
for(x = 0; x < digits; x ++) {
y = number[!prev].n[x].n + number[prev].n[x].n;
number[!prev].n[x].n = (y%1000);
number[!prev].n[x+1].n += (y/1000);
}
if(number[!prev].n[digits-1].n) digits ++;
}
printf("\nfib(%i) = %i", n, number[!prev].n[digits-2].n);
for(x = digits-3; x >= 0; x --) {
printf(",%03i", number[!prev].n[x].n);
}
printf("\n");
if(n>1) {
printf("\nfib(%i) = %i", n-1, number[prev].n[digits-2].n);
for(x = digits-3; x >= 0; x --) {
printf(",%03i", number[prev].n[x].n);
}
printf("\n");
}
if(kbhit()) getche();
return 0;
}

The commented-out fprintf() slows it down a lot, but shows the program is doing something.

The reason all the prompts and stuff are printed to stderr is that I usually redirect stdout to a file to save the result.

200,000th in 1.7 seconds? How fast is your computer?