> This isn't a very fair comparison as the Lisp code is shown running in the REPL, not in some sort of release mode that, even in Lisp, would presumably not dro

> This isn't a very fair comparison as the Lisp code is shown running in the REPL, not in some sort of release mode that, even in Lisp, would presumably not drop you into the REPL. This is not correct. There isn't such distinction between "release mode" and "debug mode"; the runtime -which includes the repl, interactive condition debugging and other nicetimes- is always available. It is not a thing you only get "in debug mode". What you can do, if you want, is to enable some optimizations and drop some debug info. For example you can put, on your code: (proclaim '(optimize (speed 3) (safety 0) ( debug 0))) ... and this will tell the compiler that your code wants ludicrous speed, that you don't care about safety or additional debug info. But you will still have the repl and everything.