(CW == conventional wisdom?) There are probably a few reasons for that. Many more programmers these days probably get their start with "scripting" languages li

(CW == conventional wisdom?) There are probably a few reasons for that. Many more programmers these days probably get their start with "scripting" languages like Python, Ruby, Perl, PHP, and JavaScript. Compared to these other dynamic, high-level languages, you probably could call Common Lisp "screaming fast". (Of course, I'm aware that there is very active implementation work going on for several of those languages that is probably doing a good deal to close the gap.) On average, though, CL is probably in the same ballpark as Java, and can sometimes be made as fast as C or C++ with a lot of effort. Also, note that Common Lisp is very much a many-implementation language (in contrast to languages like the ones above that, for most of their history, were defined by their single implementation), and different implementations make difference performance trade-offs. For much of recent history, the very high performance CL implementations have been somewhat out of reach of the typical student, hobbyist, or other weekend hacker that probably makes up most of the Lisp community. Commercial CLs are quite expensive, and high-performance free CLs like CMUCL have historically not been too friendly to beginners. When I came to Lisp, it seemed much easier to get started with CLISP (an extremely portable bytecode-compiled implementation) than with CMUCL. More recently, SBCL (an offshoot of CMUCL) and Clozure CL have made a lot of progress towards providing a go-to open source CL implementation with very good performance.