Firefox Tweaks

Performance

// speed up them sites
network.dns.disablePrefetchFromHTTPS = false
network.predictor.enable-prefetch = true
network.http.max-persistent-connections-per-server = 12

Usability

// Restore system print preview
print.tab_modal.enabled = false

Security

// Upgrade sites to HTTPS where available:
dom.security.https_only_mode_https_first = true

Ublock Origin

Settings > Block fonts = true