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File activity to AppData seems pointless

New User

File activity to AppData seems pointless

Windows 7 Home Premium FF 20 Internet Explorer 10


FF shows disk activity; IE does not

I disabled all FF add-ons.

Typical entry from procmon log shows this sequence repeated rapidly on the same file:

CreateFile QueryNetworkOpenInformationFile CloseFile CreateFile QueryBasicInformationFile CloseFile

The file is


The file is a portion of the page; it is not a particular image. Part of the page's dynamic content is in the png file, but that content changes slowly. FF is recording unchanging content in the png file.

This disk I/O is heavy, and disks don't last forever. Any thoughts on how I can stop this?

Tags (2)
Site Moderator

Re: File activity to AppData seems pointless

hello, this is the thumbnail service generating a preview image of the site that is used for the new tab page & other purposes.

you can disable that: enter about:config into the firefox location bar (confirm the info message in case it shows up) & right-click somewhere on the page. then create a new boolean preference named browser.pagethumbnails.capturing_disabled. double-click it and change its value to true.

New User

Re: File activity to AppData seems pointless

Much improved. Thanks!

Now procmon shows activity several times per second to C:\Users\RJD\AppData\Local\Mozilla\Firefox\Profiles\t6qon3e3.default-1366132150518\Cache\_CACHE_001_ C:\Users\RJD\AppData\Roaming\Mozilla\Firefox\Profiles\t6qon3e3.default-1366132150518\prefs-1.js C:\Users\RJD\AppData\Roaming\Mozilla\Firefox\Profiles\t6qon3e3.default-1366132150518\places.sqlite-shm

This differs, depending on the page being displayed.

I suppose FF needs to keep track of stuff, but I have a feeling I don't need much of this stuff.

I see "cache" in a number of entries in the config file, e.g. browser.cache.check_doc_frequency, browser.cache.disk.enable, etc.

Where is the file that contains the config info (so I can back it up, in case I break it)?

Site Moderator

Re: File activity to AppData seems pointless

hello, when you go to C:\Users\RJD\AppData\Roaming\Mozilla\Firefox\Profiles, is there more than one subfolder listed (which shouldn't be the case unless you've manually created more than one profile) - it looks a little bit like your profile is write protected which will lead to several problems (in your first question the profile you referred to was gr1kb0ju.default, now it seems to be t6qon3e3.default-1366132150518; in addition the prefs-1.js referenced will only be created if changes cannot be written to the original configuration file).

please make sure that the C:\Users\RJD\AppData\Roaming\Mozilla\Firefox\Profiles folder & all of its subfolders and containing files are not write-protected & that firefox.exe isn't prevented or sandboxed by security software to write in these directories.

to answer your questions specifically:

  • under normal circumstances the prefs.js file inside your profile folder will hold your whole configuration from about:config, so you could backup this file before you adjust any more settings
  • if you want to disable the cache on your disk an reduce i/o-activity this way, turn browser.cache.disk.enable in about:config to false
  • firefox has to read/write into prefs.js, since its configuration is stored there - so there's no way to circumvent this
  • when you visit sites firefox per default will create a history - that's what is written into places.sqlite-shm. you could set firefox to never create a hsitory (aka. always run in private browsing mode) in firefox > options > privacy which will presumably result in less disk activity.
New User

Re: File activity to AppData seems pointless

Thank you very much for your thoughtful response.

Maybe Firefox's disk activity will make my disk fail a little bit too soon, but the issue is not all that painful. I have more than one profile. To remove that issue, I can re-install Firefox, and set the config parameters as you advise.

In case this helps with anything...

Local -

In C:\Users\RJD\AppData\Local\Mozilla\Firefox\Profiles, there are three profile folders:

gr1kb0ju.default is an empty folder created yesterday, 16 April muq9ituu.Simple contains files from back in February. No prefs files t6qon3e3.default-1366132150518 contains current files. No prefs files

Roaming -

In C:\Users\RJD\AppData\Roaming\Mozilla\Firefox\Profiles, there are two profile folders:

muq9ituu.Simple contains files from back in February. Has old prefs.js t6qon3e3.default-1366132150518 contains current files. Has current prefs.js

muq9ituu.Simple and t6qon3e3.default-1366132150518 are in both Local and Roaming.

Profile manager shows profiles Simple and default-1366132150518.

I find no write-protected files in the profile folders, but the "write-protected" box in the Properties dialog boxes for folders was gray..