Hayago (早碁) is the Japanese word for quickplay go.
The first tournament which used the word, Hayago Meijin in 1954, gave players four hours of thinking time each when most other tournaments allowed about 10 hours.
From the late 1960's it often means TV games, played in some form of byoyomi or overtime. The format proved popular among spectators and many hayago tournaments were created since in Japan and other countries.
Even today, the Agon Cup, which includes "hayago" in its official name, allows 1 to 2 hours of thinking time for each player.
"Blitz" tend to mean still quicker games.