It is my pleasure to announce the acceptance of the following paper to the next International Lisp Conference, to be held at MIT, Cambridge, March 2009. CLOS Efficiency: Instantiation -- on the behavior and performance of Lisp, part 2.1 -- This article reports the results of an ongoing experimental research on the behavior and performance of CLOS, the Common-Lisp Object System. Our purpose is to evaluate the behavior and performance of the 3 most important characteristics of any dynamic Object Oriented system: class instantiation, slot access and dynamic dispatch. This paper describes the results of our experiments on instantiation. We evaluate the efficiency of the instantiation process in both C++ and Lisp under a combination of parameters such as slot types or classes hierarchy. We show that in a non-optimized configuration where safety is given priority on speed, the behavior of C++ and Lisp instantiation can be quite different, which is also the case amongst different Lisp compilers. On the other hand, we demonstrate that when compilation is tuned for speed, instantiation in Lisp becomes faster than in C++. -- Resistance is futile. You will be jazzimilated. Scientific site: http://www.lrde.epita.fr/~didier Music (Jazz) site: http://www.didierverna.com EPITA/LRDE, 14-16 rue Voltaire, 94276 Le Kremlin-Bicêtre, France Tel. +33 (0)1 44 08 01 85 Fax. +33 (0)1 53 14 59 22