Technology has moved forward. The design world no longer relies on CS5. The alternatives listed above—especially Inkscape (for free, truly portable) and Affinity Designer (for professional, affordable)—offer better performance, wider file support, and absolute peace of mind.
However, a niche yet persistent search term surrounds this legacy software: Adobe Illustrator CS5 portable
However, for professional work, the security risks and compatibility hurdles of using unauthorized portable software often outweigh the benefits. If you need a lightweight vector tool, exploring modern, legitimate alternatives is usually the safer and more productive path. Technology has moved forward