A "portable" version of Visio 2010 is a modified package designed to run without being formally installed on a Windows operating system. This is typically achieved by virtualizing the application's file system and registry entries into a single executable file.

Even as a legacy tool, Visio 2010 Professional and Premium editions offer advanced diagramming tools that many modern web-based alternatives lack:

Microsoft Visio 2010 remains a specialized favorite for IT professionals and business analysts who value its robust offline features and data-linking capabilities. While "portable" versions are often sought for their convenience—allowing you to run the software from a USB drive without a standard installation—it is important to understand the technical requirements and security risks involved in using this legacy software today. What is Microsoft Visio 2010 Portable?

Officially, Microsoft does not provide a "portable" version; these are usually created by third parties. Key Features of Visio 2010 (64-Bit)