V 5.1.0 logging

I don't seem to be able to turn off logging in Portable WinSCP 5.1.0 (Build 2625)
It shows as off in GUI and Logging=0 in ini file, but it still creates quite verbose log Data\settings\winscp.log

Running on Win XP connecting with SCP.
Until now I used v. 4.9.1

Also README suggests that WinSCPPortable.ini file should be used... this doesn't work - the ini file has to be winscp.ini

Sorry, we are not supporting Portable WinSCP, it's an independent project.
Though you can use the original WinSCP in portable manner:
https://winscp.net/eng/docs/portable