I have used a lot of portable of PortableApps, including Google Chrome Portable.
I was happy when Google Chrome Portable save cache in the Temp folder, and delete cache automatically on exit.
But I do not see this in Opera Portable, SRWare Iron Portable. Its save cache in *Data\User\Default\Cache and not delete cache automatically on exit. This is not consistent with Portable.
Thank you for attention my opinion. Wish you good health.