Frugal installation
https://mxlinux.org/wiki/system/frugal-installation/

Introduction
A frugal install goes onto an existing partition and can co-exist with other frugal installs, with installed Linux or installed Windows. The major benefit is you get to take advantage of the speed and size of an internal drive, up to literally ten times faster! If you are starting out with a usb-3 live-usb in a usb-3 port then the speedup will be less dramatic, but from a live-dvd then prepare to have your mind blown.