"Breakneck" means very fast or extremely dangerous, often referring to speed or actions that are reckless and may lead to harm or disaster. Full definition
Soaring through the skies as Pit may seem serene, but Nintendo is throwing combat chaos at breakneck speeds at Pit from beginning to end. (gamedynamo.com)
The game continued at breakneck pace for the remainder of the half, and there could be no doubt that it was the hosts who looked the most dangerous of the two teams. (liverpoolfc.com)
Driving on walls, inside cylindrical tunnels, destroying bridges and obstacles, and barrel rolling off massive jumps at breakneck speeds of 400 - 700 km / h is incredibly satisfying. (deathbybeta.com)