When the word came into English from French in the 15th century, it seems to have been in the modern sense - an occasion of sumptuous feasting. A century later, a slighter sense emerged - the one usually found in Shakespeare, where a banquet (often spelled banket) is a light meal - what we would today describe as "refreshments", or even just one part of such a meal - appetisers or dessert.
The slighter sense is shown by the adjectives when Capulet talks of "a trifling foolish banquet" (Romeo and Juliet, I.v.122) or Timon talks of "an idle banquet" (Timon of Athens, I.ii.152). The concept of a huge feast would make no sense when Sly is said to have "a most delicious banquet by his bed" (The Taming of the Shrew, Induction 1.37). A banquet, moreover, can be prepared in a rush: Enobarbus tells the servants to "bring in the banquet quickly" (Antony and Cleopatra, I.ii.12). And the sense of a light meal taken hurriedly is captured in Henry VIII, where there are two references (I.iv.12, V.iv.64) to a "running banquet".