Hi,
I don't know how to increase Ram for default Opera, maybe there is something here.
But:
Chek TaskManager - Shift+Esc | Opera Menu - Developer Check on a Clean Profile [*] Install TabUnloader from Addons.Opera.com Install Anti Mining lists from FilterLists.com On Opera's AdBlocker [Settings] On uBlock - Addons.Opera.com[*] New Profile, rename yours, Tip's info.
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"Off Topic Tip"
Follow the Signature's Backup | Reset link.
Take the opportunity to start a Backup plan and even create a Template Profile.
Windows 7 (x64)
Opera Test profile | Opera Backup | Reset