OS laggy after echoing a string in file descriptors 0,1,2 (stdin, stdout, stderr)

Question

I was trying to exploit capacity leaking to a C program (see below), by taking advantage of the non-existence of fclose() function to a file, that the program previously opened.

In short, the exploitation included the following command

sudo echo some_random_string >&3

The thing is I run the same command using >&2, >&1 and >&0, as well (stdin, stdout, stderr).

My PC lags since then (for example mouse click doesn't work on browser from times to times)

Any idea about what is going on?

The C program is the following:

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>

void main() {
    int fd;
    char *v[2];

    fd = open("/etc/zzz", O_RDWR | O_APPEND);

    if ( fd == -1 ) {
        printf("Cannot open /etc/zzz\n");
        exit(0);
    }

    printf("fd is %d\n", fd);

    setuid(getuid());

    v[0] = "\\bin\\sh"; 
    v[1] = 0;
    execve(v[0], v, 0);

}