I feel that most of our traffic tie ups, especially in GTA, are initially caused by differences in vehicle speeds. A car travelling 140 (because there is no enforcement) in the far-left lane comes upon a car doing 130 and the brake lights have to come on. Then 140 decides to attempt to cut the guy off in the middle (brake lights come on) just so he can get around 130. This happens over and over because 140 keeps coming upon cars going slower. The brake lights cause everyone who sees it to tap the brakes because they're usually following too close and if not, they take their foot off the gas. This makes the problem worse and compounds farther back. Eventually, a KM back someone is so hard on the brakes that the traffic needs to stop.
Increasing the speed limit will only exasperate this issue. Faster cars will continue to come upon slow vehicles and slower trucks.
More enforcement needs to be in place. More officers on the road keeping the cowboys who want to drive 10+km/hr faster than the fastest car in check. Just a presence would help as nobody drives crazy when a black and white is nearby. A law about keeping right except to pass could get the center lane hold outs out of the way and that would greatly benefit too.