Clojure is a new Lisp on the block. It runs on the JVM, giving it full access to any Java library (and its complement), but it leans more towards the functional paradigm, so data structures are immutable (a big boon for concurrent programming, as locks become obsolete).
In addition to supporting the usual data types of Lisp, Clojure has added syntactic support for vectors, maps and sets. Some sacrifices have been made for performance; in order to have immutable data structures, it returns a new data structure for each mutation. However, because the parent data structure is immutable, much of the structure can be shared. Performance-wise, Rich Hickey has stated that “I’ve tried to keep [operations] all within 1 to 4 times [the equivalent] Java data structure, [but lookup times are frequently faster]“.