Cooking/cooking with gas

The complete expression that is still sometimes heard is, “Now you’re cooking with gas” which dates from the early 20th century. It means making advanced progress, which of course gas cooking was during the late 19th/early 20th century. The expression is American but because gas is no longer the novelty it was, the expression has largely been reduced to ‘cooking’ which is colloquial for activity or excitement from about the 1930s.