Mozilla tests more content processes in Firefox Nightly


by Martin Brinkmann on October 12, 2018 in Firefox – 1 comment

Mozilla changed the number of content processes that the Firefox Nightly browser uses recently. The organization increased the number of content processes from four to eight in the browser.

The Firefox web browser uses multiple content processes to improve stability and security. Websites and services that are opened in Firefox are automatically assigned to a content process. Multiple independent sites share content processes in Firefox which is different from Google Chrome which uses one process per site.

Both methods have advantages and disadvantages. The use of fewer content processes reduces the RAM usage that each content process adds to the overhead but it is better for stability, security and privacy if sites are put into individual processes.

Mozilla launched the browser’s multi-process architecture in 2016 in Firefox Nightly and enabled multiple content processes in Firefox 54 Stable.

Tip: All supported versions of the Firefox web browser come with a setting to change the number of content processes used by Firefox.

Firefox Nightly users who check the number of content processes may notice that Mozilla bumped the number from four to eight in a recent update.

firefox nightly processes

There are two main ways to check the number of content processes in Firefox:

Option 1:

  1. Load about:support in the browser’s address bar. This opens a troubleshooting page with lots of information about the browser.
  2. Scroll down until you find Web Content Processes under Application Basics.
  3. The value lists the number of active content processes followed by the maximum content processes.

Option 2:

  1. Load about:config in the browser’s address bar. This opens the advanced configuration of Firefox.
  2. Confirm that you are careful if this is your first time opening the page.
  3. Search for dom.ipc.processCount
  4. The value that you see listed for the preferences is the maximum number of content processes that Firefox supports.

What is next?

Mozilla plans to run additional test to get more data. Initial measurements showed an increase of about 40 Megabytes of RAM per process based on that.

Depending on how tests go, Mozilla may increase the number of content processes in Firefox Beta and Stable eventually as well or keep the current number of content processes instead.

Firefox will use more RAM if Mozilla goes ahead with the change. Users who do not mind editing config entries may test the change right now in Firefox Stable to see how the content processes increase affects RAM usage on their devices.

I changed the number of content processes in Firefox ever since Mozilla unlocked that option to eight and had a great experience with that value. I have to admit that I did that on a system with plenty of RAM (32 Gigabytes) and that mileage may vary if the computer has 4 Gigabytes or even less.

Mozilla could consider adjusting the number of content processes based on a device’s RAM.

Interested users can follow development on Bugzilla@Mozilla.

Now You: How many content processes is ideal in your opinion?