How to find them: Go to archive.org and search exactly: "windows vista lite" (with quotes) or use the advanced search: collection:software AND subject:"vista lite".
First, a critical distinction: Windows Vista Lite is not an official Microsoft product. windows vista lite archive.org
Instead, it is a catch-all term for a series of unofficial "custom" ISO images created by hobbyists (often from communities like Zone94, TeamOS, or Ru-Board) between 2008 and 2012. The goal was simple: strip Windows Vista Service Pack 2 (or SP1) down to its bare bones to run on legacy hardware (Pentium III/Celeron) or low-RAM virtual machines (256MB–512MB). How to find them: Go to archive
If you just want a fast, low-resource Windows Vista: low-resource Windows Vista: