So now I have to wait for a minute for the tabs to load then terminate their processes from the task manager, to reduce the memory footprint of the browser.
Firefox and Chrome do not even attempt to load tabs if the memory is low, and unload them from memory if they haven't been used for a while. I have never seen Opera do that.
It used to be that launching opera with 30+ tabs, on a 4 GB ram laptop, was no issue because only one tab would load in each window but now Opera pushes the memory usage to more than 90% after launch.
The old behaviour is much more preferable to me.