John, if you're not against, I will open a new topic for this little issue - I shouldn't have posted this in my "[Fixed] GIMP Portable 2.8.0 Rev 3 - Local Help error" topic
For some odd reason, *.tmp folders (names like nsr2D9B.tmp) are left in system %TEMP% directory.
It's not related to browsing help (as John has supposed in https://portableapps.com/node/32124#comment-194220 )
I do not open help and this still happens.
The folder is created when GIMPPortable.exe starts and contains:
When GIMP is closed, the folder remains with registry.dll in it.
As I open and close the program - the number of folders grow.