Portable versions can be slightly slower due to runtime virtualization. Optimize as follows:
Fix: Copy the entire PhotoshopCS6 folder from the USB to the local C:\Temp\ drive. Run it from there for editing. When done, copy your work back. This massively improves speed. Adobe Photoshop CS6 Portable Multi language
If you have obtained a legitimate portable copy (e.g., you created it yourself from your licensed CS6 installation using tools like Cameyo or VMware ThinApp), here is the typical workflow: Portable versions can be slightly slower due to