Weybridge Computer Services


Firefox high disk usage - SOLVED

Firefox high disk usage - SOLVED
WCS.Tony - Tue Sep 26, 2017 @ 06:53AM
Comments: 2

I keep an old XP machine as some of my customers are still on XP, and over the years I have amassed loads of little utilities and free programs.

A few weeks ago I started to notice very high Disk I/O Reads for Firefox in XP's Task Manager. At first I thought that it was "just" Firefox, but it began impacting on my PC usage and to be honest I was getting concerned about how long my old disk drive would last. After an hour or two of browsing I was seeing 16,000,000,000 I/O reads or more. Yes 16 GB or more!

  • So I uninstalled a few suspect add-ons - same problem.
  • Run Firefox in safe mode - same problem.
  • Defragged and used FIREMIN to compact the Firefox database - seems faster but same problem.
  • Scouring several sites (#1) on the Internet came back with some changes to about:config parameters - same problem.
  • Whatever I did, Firefox would read and read and read.

So I user Sysinternal's excellent Process Monitor to look at FIREFOX.
Then selected one of the disk / file items and then go to Tools > File Summary

Sorting into Read Bytes soon showed the file that was causing all the reads.

It was the file with certificates file / database.
C:\Documents and Settings\user\Application Data\Mozilla\Firefox\Profiles\xxxxx.Default1\cert8.db

I closed Firefox and renamed the file cert8.db.old and opened Firefox again, a new cert8.db was created. AND my disk I/O was back to normal, after several hours browsing 413,889,378 (a bit better than before?). 

Obviously if you have any certificates that you want to keep export them before changing the cert8.db name. In Firefox - to see certificates (or export them) go to Options->Advanced->Encryption->View Certificates.


Other things I found on the Internet before finding the problem with cert8:

https://www.servethehome.com/firefox-is-eating-your-ssd-here-is-how-to-fix-it/  about:config   browser.sessionstore.interval set it to 30K (it was 15K), then 300K.
Similar findings in:
     suggests “1500000” = 25 min.

Also changed browser.sessionstore.resume_from_crash to FALSE (it was true)

All of these reduced disk usage A BIT, but did not cure the actual problem.

Comments: 2


1. John   |   Thu Oct 12, 2017 @ 02:20PM

That was great HAD SAME PROBLEM


2. Genaro   |   Sun Apr 15, 2018 @ 05:37AM

Thanks, had this problem for more than a year and now its gone. Thank you.

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