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Response time appears to be much higher on 7.78 version of libcurl (vs 7.60 version)

From: Question Throwaway via curl-library <>
Date: Fri, 17 Sep 2021 16:43:22 -0500

Hello all,

I'd like to preface this message by explaining my current setup and how I
use libcurl, and that I've at least isolated it to the libcurl realm (I

- I use libcurl in OpenWRT
- I compile libcurl with ca-bundle and mbedtls
- I use libcurl to make requests and gather response times - where the
response time critical to the functionality of the app - and have been
running libcurl 7.60 for over a year with very consistent results

Using the above, I've setup a couple of tests where I send HTTP requests to
a web server, and made a super simple (and hacked together) test to
visually see the difference. The network conditions for both of the tests
I've done are exactly the same, so I don't believe it's a network related

(Code /libcurl setup)

#include <stdio.h>

#include </usr/local/include/curl/curl.h>

#include <string.h>

#include <stdlib.h>

#include <unistd.h>

int main()


                CURL * curlhandle = curl_easy_init();

                char url[500] = "";

                if(curlhandle == NULL)


                                return 0;


                curl_easy_setopt(curlhandle, CURLOPT_URL, url);

                char version[500];

                sprintf(version, "Version: %s \n", curl_version());


                curl_easy_setopt(curlhandle, CURLOPT_NOBODY, 1L);

                curl_easy_setopt(curlhandle, CURLOPT_IPRESOLVE,

                curl_easy_setopt(curlhandle, CURLOPT_TIMEOUT, 30L);

                curl_easy_setopt(curlhandle, CURLOPT_CONNECTTIMEOUT, 45L);

                curl_easy_setopt(curlhandle, CURLOPT_NOSIGNAL, 1L);

                curl_easy_setopt(curlhandle, CURLOPT_HTTP_VERSION,

                curl_easy_setopt(curlhandle, CURLOPT_ACCEPT_ENCODING, "");

                curl_easy_setopt(curlhandle, CURLOPT_FOLLOWLOCATION, 1L);

                curl_easy_setopt(curlhandle, CURLOPT_MAXREDIRS, 2);

                curl_easy_setopt(curlhandle, CURLOPT_CAINFO,

               curl_easy_setopt(curlhandle, CURLOPT_PROTOCOLS,

                curl_easy_setopt(curlhandle, CURLOPT_SSL_ENABLE_ALPN, 1L);

                char requestStr[500];

                sprintf(requestStr, "Making 100 requests to %s \n", url);


                double response_time = 0.0;

                char str[900000];

                char avg[900000];

                long response = 0;

                double total_response_times = 0.0;


CURLINFO_TOTAL_TIME, &response_time);

                                sprintf(str, "Response time for %d: %lf
\n", i, response_time);


                                total_response_times = total_response_times
+ response_time;


                average_response_time = total_response_times /

                sprintf(avg, "Response time average for %s for %i
iterations: %lf \n", url, numIterations, average_response_time);



                return 0;


With 7.60 I regularly will get an average of 450-500MS response time

With 7.78 I regularly get between 4000-5500MS response time

This just doesnt seem right to me, and the only way I've found to fix the
issue with my actual app I run on my device is by 'frankenstein'ing the old
version of libcurl into the new firmware. I FEEL as if I'm just missing a
new setting or something has just changed, but I've gone up and down
through the libcurl documents, and still can't figure out what I might be
missing. I'm really hoping that maybe someone on this list might have
noticed the same thing / know what I might be missing.

Thanks in advance,

Received on 2021-09-17