Fairly detailed walkthrough of how I get memory leaks with Opera (versions 18 to current)
Ever since I switched to Opera Next (around version 18 or so I think?) I've noticed that eventually, no matter what I do, I end up with memory leaks that eventually completely halt my computer. Sometimes it takes up to a week, sometimes only half an hour, but it always happens at some point after I've launched Opera.
Here's a fairly detailed walkthrough of how it plays out: I have 16 GB of RAM, and after I start the computer I'm using about 10-15%. After I launch Opera I tend to be using about 30%. Even if I close Opera down I'm still using about 30%. After a while I tend to end up using in the range of 50-60% when Opera is running, dropping back down to 30-40% when I close it. Then at some unpredictable point the memory eating really starts, quite quickly getting all the way up to 95-99% and the computer grinds to a halt. If I notice this early enough (say at 90%) and can just manage to shut down Opera the memory eating stops. However the memory isn't released, and Task Manager doesn't really show what's using it either. At this point, if I check Resource Monitor I can see opera processes still hanging there, using quite a bit of memory (though not really enough to account for the whole 16 gigs), and those processes are completely unkillable. Only way to do anything useful at this point is to restart the computer.
Now it might sound like the problem isn't necessarily related to Opera since Windows doesn't really show Opera using enough memory to cover the whole usage, but three facts work against this:
I never got this exact behavior before I switched over to the new, post 12.0 Opera.
It has so far at least never, ever happened if I haven't started Opera at least once. I've recently tried to use Firefox to see if I can run it without memory problems. So far it seems that Opera is the culprit, setting up the exact same sessions in FF I'm using about half the amount of RAM, and where my longest uptime record with the new Opera running is 7 days before memory leak problems (been using new Opera for about a year, been consistently getting those memory leaks during the whole time), with FF in the past two months I've had two sessions that lasted two weeks (restarted manually due to updates) and my latest has been going on for a month. So not starting Opera has allowed me to run a session that's so far about 4 times as long as the longest I've managed with Opera in a year. In fact since I stopped using Opera I haven't seen one memory leak.
Type of Opera usage seems to affect things. Flash particularly seems like poison, especially YouTube videos with the flash player. Turning flash off and using HTML5 video more consistently allows me to run about a week without a leak (not a guarantee though) and keep the memory usage lower overall.
So problems began after I started using the new version of Opera, how I use Opera affects the prevalence of the problems, and not using Opera at all has so far seemed to completely eliminate the issue.
Still, I really wish I could get back to using Opera. I've been using different versions of Opera for roughly 13-14 years now, and have always thought them to be superior to other browsers. I've just about managed to get FF to work like the new Opera, but it took a buttload of extensions to get there, and overall the experience doesn't feel as smooth and cohesive (because the extensions have been done by different people), and I'm still missing quite a few things. I see it as a temporary solution while Opera gets fixed. Chrome isn't even really worth mentioning, it lacks so much functionality it's not even funny, everything would have to come from extensions...
This is even sadder because the recent versions of Opera had almost gotten back to the level of Opera 12 in overall experience, and clearly ahead in some particulars. By this I mean no disrespect to new Opera, just that it's still a work in progress and somewhat limited in many aspects compared to 12, which over the years had managed to get just about everything you could hope for inside it, and managed it without feeling overtly complex or clunky. By version 23-25 there was very little to complain about though, apart from the memory leaks...
Incidentally, Opera 12 also suffered from some form of memory leaking on three of my computers. It took a long long time, never completely crashed the computer and usually involved me running about 150 tabs in three windows (my usage method was to rather have commonly used pages in open tabs all the time instead of opening them via bookmarks or similar, plus my usage usually involves massive amounts of crossreferencing different pages), but at some point images started being rendered as black boxes, new pages struggled to open, closing Opera didn't release even nearly all of the memory it was using, etc. So memory leaks seem to be a bit of a tradition for Opera, but at least before they were a minor nuisance that came with very heavy use over long periods of time, now they can happen within minutes with only about 10 tabs open.
If there's anything I can do to help further testing, please let me know, I really want to get back to the best browser on the market.