Common Lisp is not a runtime, it’s a specification. Implementations are free to compile everything to fast native code, or to interpret everything. Various available implementations do that and everything in between. That said , SBCL and the commercial implementations can be extremely fast, especially if you specify types on tight loops. SBCL comes with a disassembler that shows you right in the REPL the Assembly a function compiles to so you can even get close to C performance.

Addedum that having a disassembler is quite common language primitive in most compiled Lisps, since early days.