Disabling IPv6 on Firefox

Firefox on my laptop feels slow of late, and it seems to be a problem relating to DNS resolution. I looked up some possible fixes and found that IPv6 settings on the browser may have something to do with it: with IPv6 enabled, Firefox makes an additional DNS request.

You can disable IPv6 on Firefox by typing about:config on the address bar, searching for network.dns.disable.ipv6, and setting this to true.

I've seen some improvements after this "fix." More updates to follow.