tl;dr: If you need a quick way to test any API or server-side rendered (SSR) web page, use ab -c 10 -n 100 "https://example.com/" which says issue 10 concurrent out of 100 total requsts. This Apache benchmarking tools then displays performance statistics.

apt install apache2-utils

ab -c 10 -n 100 "https://borza.blog/"

This is ApacheBench, Version 2.3 <$Revision: 1901567 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking borza.blog (be patient).....done


Server Software:        cloudflare
Server Hostname:        borza.blog
Server Port:            443
SSL/TLS Protocol:       TLSv1.2,ECDHE-RSA-CHACHA20-POLY1305,2048,256
Server Temp Key:        ECDH X25519 253 bits
TLS Server Name:        borza.blog

Document Path:          /
Document Length:        8184 bytes

Concurrency Level:      10
Time taken for tests:   1.372 seconds
Complete requests:      100
Failed requests:        0
Total transferred:      894992 bytes
HTML transferred:       818400 bytes
Requests per second:    72.91 [#/sec] (mean)
Time per request:       137.150 [ms] (mean)
Time per request:       13.715 [ms] (mean, across all concurrent requests)
Transfer rate:          637.27 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:       39   55  12.0     53     126
Processing:    33   50  30.2     42     237
Waiting:       32   48  29.9     41     237
Total:         76  105  36.4     96     310

Percentage of the requests served within a certain time (ms)
  50%     96
  66%     99
  75%    104
  80%    109
  90%    124
  95%    164
  98%    304
  99%    310
 100%    310 (longest request)