Gary Illyes from Google confirmed yesterday that GoogleBot does not support HTTP pipelining. The truth is, most modern browsers don’t support it either by default. Here is Gary’s tweet on the subject:

HTTP pipelining is a technique in which multiple HTTP requests are sent on a single TCP (transmission control protocol) connection without waiting for the corresponding responses.

This concept is supported in HTTP/2, the specific technique was superseded by multiplexing via HTTP/2, which is supported by most modern browsers and is likely supported by GoogleBot.

So if your site is over HTTP/2, it can benefit from this technique but the old version of HTTP pipelining is not supported by GoogleBot.

Forum discussion at Twitter.