Here lies the elephant in the room: Security. Sony never officially released a "Portable" version of Vegas Pro 9. These executables are "repacks" or cracked versions modified by third parties to bypass installation.
Because there is no splash screen loading dozens of background services (looking at you, Adobe Creative Cloud), Vegas Pro 9 portable launches in roughly 2 to 3 seconds on an SSD. For quick cuts and rapid rendering of gaming clips or vlogs, it is exceptionally fast.
Do you have a netbook from 2009 with an Intel Atom processor and 1GB of RAM? Modern software will refuse to even launch. Vegas Pro 9 Portable will not only launch; it will edit SD (Standard Definition) footage like DV-AVI or MPEG-2 surprisingly well.