Personal configuration setting for a more performant/pleasing Firefox, at the expense of more RAM usage.

user.js

// Default font
user_pref("font.internaluseonly.changed", true);
user_pref("font.minimum-size.x-western", 12);
user_pref("font.name.monospace.x-western", "JetBrains Mono");
user_pref("font.name.sans-serif.x-western", "Cantarell");
user_pref("font.name.serif.x-western", "Cantarell");
user_pref("font.size.monospace.x-western", 14);
user_pref("font.size.variable.x-western", 18);

// Reading mode
user_pref("reader.color_scheme", "sepia");
user_pref("reader.font_size", 10);
user_pref("reader.font_type", "serif");
user_pref("reader.line_height", 6);

// Some customisation
user_pref("devtools.cache.disabled", true);
user_pref("devtools.theme", "dark");
user_pref("browser.tabs.loadBookmarksInTabs", true);

// Optimisations
user_pref("media.hardware-video-decoding.force-enabled", true);
user_pref("gfx.webrender.all", true);
user_pref("gfx.webrender.compositor", true);
user_pref("gfx.webrender.compositor.force-enabled", true);
user_pref("gfx.webrender.enabled", true);
// Cache
user_pref("browser.cache.memory.capacity", 4194304);
user_pref("browser.cache.memory.max_entry_size", 1048576);
user_pref("browser.cache.disk.capacity", 1048576);
user_pref("browser.privatebrowsing.forceMediaMemoryCache", true);
user_pref("media.memory_cache_max_size", 16384);
// Disk write (session)
user_pref("browser.sessionstore.interval", 120000);
user_pref("browser.sessionstore.interval.idle", 86400000);

// Windows options
user_pref("taskbar.grouping.useprofile", true);