I use Clojure at work but wow do I miss just about everything about Common Lisp whenever I have to debug anything or want performant code. Being able to be in nested errors and click at any part of the stack to inspect lexical bindings is extremely useful, and more importantly, clicking on an object then pushing M-<RET> to copy it to my REPL is much nicer than what Clojure offers (tap>, which I consider a glorified pretty printer even if you use tools like Portal).
As for performance, well, Common Lisp lets you statically type things, and SBCL can emit really efficient code if you do this. I find it helpful to run DISASSEMBLE on my own code to see what exactly is being emitted and optimize from there. And more importantly, packages like SB-SIMD and Loopus are a god send for any number crunching application.