I have 2Go RAM so it's not the problem. And I have few tabs opened in Opera.
I think the problem is Adobe Flash which dump by 15 minutes then Opera is very slow and finally dump. Anyway I think the problem is a plugin which finally dump and makes Opera dump too.

Opera works 15 minutes, then it becomes very slow and finally dump.
What is this gave up of this software on Linux ? Before last updates, it works !
I have correctly installed all the plugins (that is hard !).
What is the problem ?