The official developer, THS, does not distribute an official portable version. Any "Portable" version you find online has been repacked by a third party, usually bypassing Steam DRM.
The tool operates by taking a windowed game and applying an overlay that performs two main tasks:
Does lossless scaling improve performance in Cities Skylines 2?
so the system has enough resources to process the extra frames. www.corsair.com Quick Setup Checklist Lossless Scaling: Everything You Need to Know - Corsair
: This version features improved Frame Generation (LSFG), which significantly reduces visual artifacts during fast movement.
: Works with any windowed application, including emulators and web browsers.