Why does Lisp need to be slower than c?
wglb: Lisp executables are fast based on good compilers. You can usually tailor your Lisp program with declarations and speed/safety trade-offs to get very good code.  There is a benchmark site called Shootout that shows how well pretty much any language compares for execution time.And if you discover that you have the wrong approach, it is much easier to change a Lisp program than a C or a C++ program.  That is my primary definition of fast.Speed of program execution is often (not always) overrated.