My preferred usage pattern for Firefox includes having 20-30 windows open, with an average of perhaps 10 tabs/window. (This is my preference, so please don't bother suggesting changing this.)

With my old machine, a ThinkPad W500 running Xubuntu 14.04 LTS (very much living up to its name, Trusty), this worked fine most of the time with 8 GB RAM and a swap partition of 12 GB. At times, it would begin to slow down due to swapping, but this would typically happen after several days (sometimes more than a week) of use, and a restart of Firefox would fix it for another period. Very rarely, but typically with more than 25 windows, the Firefox process would become very sluggish or completely unresponsive, but I would still be able to switch windows to a terminal and kill it.

Under the assumption that a faster system with more RAM would improve this situation, I obtained a (used/refurbished) T520 with 16 GB RAM preinstalled from the vendor about a week ago. However since installing this with Xubuntu 17.04 last weekend, it seems to be a worse setup than what I had before. Leaving my machine idle with just Firefox (18 windows) and Terminal (4 windows) for a day, tonight I found it in a state where it was completely unresponsive, disk light constantly on with the disk trashing, to the point where even switching to a Terminal window was effectively impossible. After waiting five minutes I gave up and pressed the power button.

This was after I yesterday tried to improve performance (having had a similar problem) by tuning FF Performance: enabling hardware acceleration and setting the Content process limit to 4. (FF 55.0.2, which I had also been using on the old system since august 20.).

What is the cause of this horrible trashing, and how - other than having less windows open - can it be prevented? Given that the old system worked fine, I am considering downgrading the new machine to 14.04, but that seems an unviable option in the long run. I am also considering changing swappiness, or even running FF under a virtual machine so I can limit its resources.

Any suggestions for finding the cause, a solution or a good workaround will be highly appreciated.

  • The Thinkpad T520 has a Nvidia graphics card. Have you installed Nvidia drivers? – user692175 Sep 18 '17 at 22:11
  • You mentioned one Firefox process but also the content process limit option. You should have more than one process (firefox + "Web Content") on working multi process/e10s setups. Please check your addons with compatibility reporter (a had a few which weren't compatible) and that you meet all requirements. I'd recommend to start with a clean profile on both machines to analyze the problem further. – LiveWireBT Sep 18 '17 at 23:20
  • @MichaelBay T520 is the first model with Intel HD Graphics (Sandy Bridge in this series), Nvidia graphics are optional and personally I'd rather not use proprietary graphics drivers, because I read that e10s was struggling with it or will not run at all. – LiveWireBT Sep 18 '17 at 23:24
  • I think this question is too broad, and isn't answerable in its current form. You need to investigate the cause of this behavior. Look at RAM usage with free -m, disk usage with iotop, CPU usage with top, check the syslog, try a FF profile without tweaks, etc. Then, if you need help interpreting the findings, add them to the question. – mikewhatever Sep 18 '17 at 23:58
  • I know that I didn't provide much information, but it is hard to investigate a system that is for all intents and purposes frozen. The reason for this question is precisely to find out if someone else had had this problem and already identified a cause (and maybe a solution.) This model (4242W38) of the T520 has no Nvidia. I have only installed what came from the Xubuntu 17.04 install DVD, and upgrades from the network. The FF profile on the new machine is a clean new profile, and no plugins/addons have been installed. – LHP Sep 19 '17 at 1:54

If 14.04 worked OK for you then there is no trouble in reinstalling it (other than possible hardware issues with components from end-2016 to 2017, and its EOL in 2019). You will have more RAM than before, so it would be better for your normal Firefox usage, and also, you will have your trusty Xubuntu 14.04 working OK.

You can stay in 14.04 until end-2019 or mid-2020, when Firefox drops support for that Ubuntu version. Then you might try future versions (18.04, 20.04...).

If you are worried about security, FYI you can still receive upgrades until Apr 2019, and after that there is a risk if you still use the system, but if modern versions won't work well, you might try other things such as Mint, Debian,etc.

  • This may end up being the workaround I will have to choose, although reinstalling is a hassle I would prefer to avoid, and Xubuntu 17.04 has a few features that I would miss. Also, it would probably just postpone the problem, unless the cause gets found and fixed in the meantime. – LHP Sep 19 '17 at 2:02

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