Why my program keeps blocking in a nondeterministic way using CURL library to do HTTP requests?

Question

I am trying to do periodic HTTP request with a time stamp of 1-2 seconds. The program runs on my Raspberry Pi Zero W. Program runs very good and fairly deterministic for the first couple of minutes, and then something happens and I don't get any response for some time, and then, after some time, it unblocks and runs ok until next blockage.

I tried to eliminate curl_easy_cleanup function execution after every http_request because I have red in documentation that curl handles shall not be cleaned very frequently, and it behaves better in reality, for some time..(it blocks again). I have also tried to call curl_easy_cleanup function in handler after every http response, but it produces seg fault.

I expect of my program to be deterministic, in a way to perform HTTP requests on every n seconds.

(This is my first Stack Overflow post, I hope that I managed to explain my question in a good way :) Here is my code:

#include <stdio.h>
#include <curl/curl.h>
#include <string.h>
#include <pigpio.h>

#define PTR_OFFSET 49
#define SIZEOF_MSG 5
#define DELAY_TIME 100
#define GPIO_PIN   25

char niz[20];
char opcija0[] = "00000";
char opcija1[] = "00001";

size_t write_callback(void *contents, size_t size, size_t nmemb, void *userp){
    
    memcpy(niz, (char *)contents + PTR_OFFSET, SIZEOF_MSG);
    size_t total_size = size*nmemb; 
    if (!memcmp(niz, opcija0, SIZEOF_MSG)) 
    {
        gpioWrite(GPIO_PIN, 0);
        printf("GPIO OFF\n");
    }
    if (!memcmp(niz, opcija1, SIZEOF_MSG))
    {
        gpioWrite(GPIO_PIN, 1); 
        printf("GPIO ON\n");
    }
    printf("Niz je: %s\n", niz);

    return total_size;
}

int main(){
    CURL *curl;
    CURLcode res;
    
    
    if (gpioInitialise() < 0)
    {
        fprintf(stderr, "pigpio initialisation failed\n");
        return 1;
    }

    gpioSetMode(GPIO_PIN, PI_OUTPUT);

    while(1)
    {
    curl = curl_easy_init();
    if (curl) {
        const char *url = "https://3704-109-245-204-66.ngrok-free.app/Filip/?y=1"; //Replace with wanted URL
        
        //Set the URL
        curl_easy_setopt(curl, CURLOPT_URL, url);

        //Set the write callback function to print the response
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);

        //Perform the request
        res = curl_easy_perform(curl);

        //Check for errors
        if (res != CURLE_OK) {
                fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
        } else {
        printf("\nRequest succesful.\n");
        }

        //Cleanup and free resources
        //curl_easy_cleanup(curl);
    
    } else {
        fprintf(stderr, "Failed to initialize libcurl.\n");
    }
        
    time_sleep(2);
    }
    return 0;
}