Opera Portable never looses settings, Extensions & Bookmarks once installed.
So if You install a new Winreduced O.S there is no need to reinstall everything.again
After installing it the first time, make a backup of it as it accumulates a lot of garbage
So You can always have a clean Opera, 
Do not copy the version Directory  of Opera when cleaning
Opera is a good & very quick Chromium Clone apart from the garbage collection
The last Opera versions can be made the default browser now

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