debugger remember past code

Here is a code where the problem is that, if I put breakpoints at the beginning of each line:

• We go from the breakpoint just before the sprint to the breakpoint just after the sprintf after 20 seconds.
• The display of string2 takes place again 30 seconds after the execution of the sprintf.
• Similarly, variables are displayed 30 seconds after each subsequent statement is executed. (And if I want to move to the next breakpoint without waiting for the display, it will then take 30 seconds before performing the instruction).

void test(const char* string1)
{
   long long int k,s,cnt,beg,end,op,s1,s1E;
   char* ptr;
   char* string2 = new char[100];
   sprintf(string2,"diff(%s)",string1);
   k = 0;
   s = 0;
   cnt = 0;
   beg = 5;
   end = 0;
   op = 0;
   s1 = 13;
   s1E = 11;
   ptr = NULL;
   char op1 [s1 ]; memcpy(op1 ,&string2[beg] ,s1 -1);
   char op1E[s1E]; memcpy(op1E,&op1[s1 != s1E],s1E-1);
}
 
int main(int argc, char *argv[])
{
   test("12345678*123456");
   return 1;
}  

For example, if I remove the line

ptr = NULL; 

, the program crashes and displays 2 small windows:

Le processus gdb s'est arrêté de façon inattendue (code 3).

Windows recherche une solution au problème.

Here (https://www.developpez.net/forums/d2170123/c-cpp/cpp/debuter/mode-debug-different-mode-release-sprintf-effectue-temps/#post12045323) is a link where we can see the debugger wait a lot to print each variable when passing through a breaking point.

Qt Creator 5.4.1

Thank you