I've installed portable apps on my hard drives for years without a problem (Firefox, VLC, many more). However, I notice VLC takes FOREVER to open compared to the "regular" (non-portable) version. This leads me to a question that people ask but I can never answer:
Are portable apps "on your PC" generally slower? If so, why? Has anyone ever tested?
The antivirus programs tend to slow down the portable versions due to the way they are compressed. Try turning off the AV and see they load quicker. I have addde an exception to my AV not to scan my PortableApps directory because of the slowness.