In practice

In practice, however, the type system constrains the programmer in many ways that are unacceptable to Lisp programmers: data cannot be interpreted as programs, lists must be homogeneous, and functions are not easily redefned without recompiling other dependent functions.

>>19
Macros are a compiler-hook, not an interpreter-hook.
Interpreters tend to be slow, compilers not so much.
You need to understand the differences between interpreters and compilers.
eval - usually interpreted, unless it calls the compiler.
defmacro - running code during compilation.