uMatrix is fantastic. I had almost given up on FF, then switched to Quantum, fast as lighting at first then slowed down and increasingly broken with NoScript, which I disabled. Then FF was slowed down with scripts, slowing down my whole PC. uMatrix saved my PC!
Bit of a learning curve. Tip: if you don't know what item to unblock, right-click and "inspect element" is your new best friend. Also lots of tutorials on YouTube (probably the first site you'll partially unblock to see the videos). Was thinking about getting uBlock but I don't think I even need it now.