Some web servers allow the encapsulation of more than one HTTP request in a single packet. This may speed up the execution of an NSE HTTP script, and it is recommended that it is used, if the web server supports it. The http library, by default, tries to pipeline 40 requests and auto adjusts the number of requests according to the traffic conditions, based on the Keep-Alive header.
$ nmap -p80 --script http-methods --script-args http.pipeline=25 <target>
Additionally, you can use the argument http.max-pipeline to set the maximum number of HTTP requests to be added to the pipeline. If the script parameter http.pipeline is set, this argument will be ignored:
$nmap -p80 --script http-methods --script-args http.max-pipeline=10 <target>