user_pref("browser.backspace_action", 2);
user_pref("browser.bookmarks.max_backups", 2);
user_pref("browser.tabs.insertRelatedAfterCurrent", false);
user_pref("browser.tabs.selectOwnerOnClose", false);
user_pref("browser.urlbar.clickSelectsAll", true);
user_pref("browser.urlbar.trimURLs", false);
user_pref("devtools.inspector.enabled", false);
user_pref("devtools.styleinspector.enabled", false);
user_pref("dom.popup_maximum", 4);
user_pref("layout.spellcheckDefault", 2);
user_pref("layout.word_select.eat_space_to_next_word", true);
user_pref("media.autoplay.enabled", false);
user_pref("network.dnsCacheEntries", 128);
user_pref("network.dnsCacheExpriation", 3600);
user_pref("network.http.pipelining", true);
user_pref("network.prefetch-next", false);
user_pref("plugins.click_to_play", true);
user_pref("privacy.trackingprotection.enabled", true);

user_pref("browser.backspace_action", 2);
user_pref("browser.bookmarks.max_backups", 2);
user_pref("browser.tabs.insertRelatedAfterCurrent", false);
user_pref("browser.tabs.selectOwnerOnClose", false);
user_pref("browser.urlbar.clickSelectsAll", false);
user_pref("browser.urlbar.trimURLs", false);
user_pref("devtools.inspector.enabled", true);
user_pref("devtools.styleinspector.enabled", true);
user_pref("dom.popup_maximum", 4);
user_pref("layout.spellcheckDefault", 2);
user_pref("layout.word_select.eat_space_to_next_word", true);
user_pref("media.autoplay.enabled", false);
user_pref("network.dnsCacheEntries", 128);
user_pref("network.dnsCacheExpriation", 3600);
user_pref("network.http.pipelining", true);
user_pref("network.http.pipelining.ssl", true);
user_pref("network.http.proxy.pipelining", true);
user_pref("network.prefetch-next", false);
user_pref("network.protocol-handler.expose.magnet", false);
user_pref("plugins.click_to_play", true);
user_pref("extensions.pocket.enabled", false);
user_pref("privacy.trackingprotection.enabled", true);

Update Firefox user.js