The American Heritage Dictionary of the English Language, circa 1970, says:
slow, adjective. Proceeding at a low speed; taking more time than is usual. Synonym: leisurely.
lane, noun. Any narrow passage, course, or track, such as a strip delineated on a street or highway to accomodate a single line of automobiles.
And Webster’s Ninth New Collegiate Dictionary, circa 1991, says:
cafe, noun. A usually small and informal establishment serving various refreshments, such as coffee.
While technically correct, those definitions are a bit sterile and provide only a hint of the answer.
The mental image I get when I think slow lane cafe is a place where one can drop in, slow down, relax, and have a leisurely cup of coffee, or perhaps a cup of tea or even a cold beer. These libations could be enjoyed alone while reading, thinking, or just staring off into space. Or they could be shared with close friends or family while discussing “life, the universe, and everything.”