On one of the websites I found an article saying what you need to do if you want to speed up Firefox 57.x a little bit and make it less chatty.
First set these settings in about:config to
false:
browser.newtabpage.activity-stream.feeds.telemetry
browser.newtabpage.activity-stream.telemetry
browser.ping-centre.telemetry
toolkit.telemetry.archive.enabled
toolkit.telemetry.bhrPing.enabled
toolkit.telemetry.enabled
toolkit.telemetry.firstShutdownPing.enabled
toolkit.telemetry.newProfilePing.enabled
toolkit.telemetry.reportingpolicy.firstRun
toolkit.telemetry.shutdownPingSender.enabled
toolkit.telemetry.unified
toolkit.telemetry.updatePing.enabled
Then you need to set
toolkit.telemetry.server to blank instead of
https://incoming.telemetry.mozilla.org
And last what you need to do is to disarm experiments which can be remotely enabled by Mozilla - just set to
false below mentioned settings in about:config:
experiments.activeExperiment
experiments.enabled
experiments.supported
network.allow-experiments
That's all!