the HN migration from Racket to SBCL is probably the best real-world case study for SBCLs native code compiler quality. going from pages of comments needing pagination to rendering everything in one shot is not a minor optimization - thats an order of magnitude improvement in throughput for a real production workload.

what doesnt get mentioned enough is SBCLs type inference. if you add type declarations to hot paths, the compiler generates code that rivals hand-optimized C. the REPL-driven development workflow where you can redefine functions in a running system is still unmatched by anything in the modern tooling ecosystem.