Increase speed

Navigate to about:config
Create a new preference called browser.tabs.remote.autostart and set it to true. This enables multi-process seamonkey.
set general.smoothScroll.msdPhysics.enabled to true for smoother scrolling
set layers.acceleration.force-enabled to true for faster graphics
set layers.omtp.enabled to true for even faster graphics

Ublock Origin extention support

https://github.com/gorhill/uBlock-for-firefox-legacy/releases