I agree 100%. Some dosy woman driver a few months ago just slammed her brakes on in a 40 zone and there was no traffic in front of her, I almost went into a skid myself trying to avoid the bitch. She didn't even know. Well she did after I overtook her bibbing the horn, shouting and sticking my fingers up at her.
And I also HATE being stuck behind peeople doing 5/10/20 under the speed limit. I have no patience anymore, I bib the horn if they're more than 10 under the limit (and if I can't overtake).