It was tested on a x86_64 Linux system. The machine is not quite new but is OK for building and running python. The test script is actually a management tool for a larger project that is not released in public so I don't have right to disclose it here. When tested on python 3.7 it did run faster than python 3.6 so there were indeed great improvements.

While optimizing standard libraries definitely makes the program start up faster, we should also note that each user program also has its own specific initialization procedure. This is in general out of control of language platform developers, but forking a user-initialized vm or using a snapshot chosen by the user still helps.