1
general::
Rapidly crowding, coming so fast they run together, as in The questions came at him thick and fast. This term originated in the second half of the 1500s as thick and threefold and was replaced by the current version about 1700. For a synonym, see FAST AND FURIOUS.
American Heritage Idioms
2
general::
Phrase(s): thick and fast
in large numbers or amounts and at a rapid rate. • The enemy soldiers came thick and fast. • New problems seem to come thick and fast.
McGrawhill's American Idioms And Phrasal Verbs