Firefox constantly trashing disk

[Tijl Coosemans]

On Fri, 14 Sep 2018 18:13:57 +0200 Andrea Venturoli <ml at netfence.it> wrote:
> Hello.
> 
> I think FireFox (ESR) on my system makes really too much disk I/O.
> My profile is on an NFS drive, but I hear local disks spinning, so I 
> guess it's writing to /tmp or /var/tmp (or another local folder).
> 
> Looks like animations are what really make him go mad: just opening 
> https://get.webgl.org/ will start heavy disk activity which will only 
> stop when that page is closed; however even a simple gallery, where 
> images "slide" smoothly, will give a spin any time a button is pressed 
> and the image changes.
> 
> I'd like to dig into this and understand what it is doing.
> 
> Is there a way I can see what file Firefox is writing too?
> I tried "lsof|grep firefox", but that will list some 1200-1300 entries 
> and I still don't know which is the one.

Try the patch in https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=222356
For Firefox ESR you may need the version hidden behind 'Show Obsolete'.