Firefox and Chrome are frankly not good at scrolling smoothly in step with fingers. I use FF on my desktop and phone, but run IE on my Surface because of this. Chrome is tolerable (smooth, but the momentum is wrong). Firefox sucks.
Haven't checked in on the Mac versions lately, but I remember the same experience in FF there a couple of years ago. It feels like scrolling was designed entirely around moving in 3-line chunks per click of the mouse wheel, with some smoothing done for longer continuous spins. Then they tried to bolt incrementless trackpad scrolling on top of that and it went really poorly.