To improve page loading, Firefox makes speculative pre-connections to sites when the user hovers mouse over a link or thumbnail on New Tab page or in the search field on the NTP or the home page.

Because of the predictive connections, there is a possibility of of client certificate selection dialog to pop up, that’s why Mozilla has decided to disable speculative connections from the address bar in Firefox 56 (which is going to be released two days later than the planned scheduled date) by default.

Mozilla disables speculative connections in Firefox 56

In Firefox 56, if you visit about:config,

This preference ‘network.http.speculative-parallel-limit’ value should have set to zero, means speculative pre-connections are disabled in Firefox browser.

If you notice the preference value as 6 than zero, then the feature is enabled.

You shouldn’t need to anything in Firefox 56 as it will be disabled by Mozilla, after fixing client certificate selection dialog pop up issue, Mozilla may re-enable it in Firefox 57.

If you’ve privacy or security concerns, you can keep the feature deactivated in current and future Firefox versions by setting the above said preference value to 0.

What’s your take on this? Do you think speculative connections should be disabled by default in Firefox browser? Let us know in the comments.